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  • FLUID MECHANICS AND HEAT TRANSFER  (362)
  • 2010-2014
  • 1985-1989
  • 1980-1984  (362)
  • 1925-1929
  • 1982  (362)
Collection
Keywords
Years
  • 2010-2014
  • 1985-1989
  • 1980-1984  (362)
  • 1925-1929
Year
  • 1
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    Full-coverage film cooling (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Transpiration cooling is treated and then full coverage discrete hole injection for three injection orientations. Spacings with pitch to diameter ratios of 5 and 10 are discussed. The array is staggered, with the transverse pitch and the streamwise pitch the same. Results are presented in terms of the Stanton number using the heat transfer coefficient defined in terms of the difference between the wall temperature and the free stream temperature. Two values of Stanton number are provided for each situation: one with the injectant at wall temperature, and the other with the injectant at free stream temperature. These two values are equivalent to knowing the heat transfer coefficient and the adiabatic effectiveness. The heat transfer coefficient thus defined is used with the actual wall temperature to and the actual gas temperature to calculate the heat load. The principle of superposition thus invoked is valid exactly when the governing equations are linear.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 27 p
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  • 2
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    Heat loss and drag of spherical drop tube samples (1982)
    In:  CASI
    Details
    Publication Date: 2006-02-14
    Description: Analysis techniques for three aspects of the performance of the NASA/MSFC 32 meter drop tube are considered. Heat loss through the support wire in a pendant drop sample, temperature history of a drop falling through the drop tube when the tube is filled with helium gas at various pressures, and drag and resulting g-levels experienced by a drop falling through the tube when the tube is filled with helium gas at various pressures are addressed. The developed methods apply to systems with sufficiently small Knudsen numbers for which continuum theory may be applied. Sample results are presented, using niobium drops, to indicate the magnitudes of the effects. Helium gas at one atmosphere pressure can approximately double the amount of possible undercooling but it results in an apparent gravity levels of up to 0.1 g.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: the 1981 NASA(ASEE Summer Fac. Fellowship Program; 31 p
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  • 3
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    Turbulent boundary layer heat transfer (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Several environmental parameters presently acknowledged to affect heat transfer are discussed including: (1) the experimental apparatus used, (2) uniform and variable wall temperatures, (3) acceleration effects, (4) deceleration, (5) free stream turbulence, (6) surface roughness, (7) unsteady effects, and (8) secondary flows. Calculation procedures, and some physically based models that are successful in computing heat transfer rates are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 40 p
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  • 4
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    Curvature effects and turbulent boundary layers (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Results are examined from an experiment conducted to determine quantitatively the secondary factors which affect the response of a turbulent boundary layer to convex curvature and to examine the recovery process after curvature ended. The variation of Stanton number with streamwise distance and with enthalpy thickness Reynolds number for the baseline case is shown. The effect of delta sub .99/R on the velocity of the potential core would have if we extended to the wall with no viscous effects, of free stream acceleration, of an unheated starting length, and of boundary layer maturity are discussed. Mixing length and turbulent Prandtl number models are reviewed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Film Cooling and Turbine Blade Heat Transfer, Vol. 1; 29 p
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  • 5
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    Analysis of the decay of temperature fluctuations in isotropic turbulence (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The Lagrangian dispersion theory of Durbin (1980) is used to analyze experiments by Warhaft and Lumley (1978) and by Sreenivasan et al. (1980) on temperature fluctuations in grid-generated turbulence. Both theory and experiment show that the decay exponent m depends on the ratio of the initial length scales of velocity and temperature, although when this ratio is greater than 2.5 such dependence is negligible. The theory shows that m is not truly constant, but within the range covered by the experiments it is nearly so. The agreement between theory and experiment lends credence to the idea that the decay of fluctuations is controlled largely by turbulent relative dispersion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 25; Aug. 198
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  • 6
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    Axisymmetric inviscid swirling flows produced by bellmouth and centerbody (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The effect of large deformation in the flow between the bellmouth and centerbody is considered analytically for application to studies of vortex breakdown in a pipe. Basic equations are defined for axisymmetric inviscid swirling flows at the inflow and outflow sections. Axial and circumferential velocity component profiles are presented, and comparisons are made with trials involving vane angles of 42 deg and Re of 2300. Axial components of the prediction matched well in the inner half of the pipe radius and not well with the outer, while circumferential predictions were good only at the axis. A lack of viscosity was concluded to result in the inaccuracies near the wall.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 20; Apr. 198
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  • 7
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    Study of incompressible turbulent channel flow by large eddy simulation (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Incompressible turbulent channel flow is investigated by large eddy simulation using improved numerical methods and boundary conditions. In downstream and spanwise directions, cyclic boundary conditions are imposed for velocity and pressure, and two types of boundary conditions near the wall are used and compared. One type is based on the logarithmic law of the mean velocity near the wall and has a slip boundary condition where the molecular-viscous term is neglected. The other type is based on a no-slip boundary condition, where fine mesh spacing near the wall is used to take account of the molecular viscosity. Although the present study employs a coarse mesh (16 x 16 x 21), its results are in good agreement with those of Moin and Kim (1981).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 8
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    Developing flow in S-shaped ducts (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The velocity characteristics of laminar and turbulent developing flow in an S-duct formed from two 22.5-deg bends of rectangular cross-section have been studied experimentally using laser Doppler velocimetry. It is shown that pressure-driven secondary flows arise in the first bend of the duct and reach maxima of 0.22 and 0.15 of the bulk velocity in the laminar and turbulent flows, respectively. The velocities are greater in the laminar flow, mainly because of the thicker inlet boundary layers. On passing through the second half of the S-duct, a secondary flow is established over most of the section in the direction opposite to that in the first half. Near the outer wall of the second bend, however, the secondary flow generated in the first bend is sustained because of the local sign of radial vorticity. This effect contributes to a redistribution of the streamwise isotachs, by the end of the duct, comparable with that in unidirectional bends.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 9
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    Stability of erythrocyte suspensions layered on stationary and flowing liquids (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The apparent stability of erythrocyte suspensions layered on stationary and flowing Ficoll solutions was studied considering the effects of particle concentration, type and size, and the different flow rates of the particle suspensions and chamber liquid. The data from the flowing system were empirically fitted and, when extrapolated to zero chamber liquid flow rate, gave values comparable to the data from the stationary system, thus confirming the validity of the data and our approach to obtain that data.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Separation Science and Technology; 17; 6, 19; 1982
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  • 10
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    Cauchy integral method for two-dimensional solidification interface shapes (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A method is developed to determine the shape of steady state solidification interfaces formed when liquid above its freezing point circulates over a cold surface. The solidification interface, which is at uniform temperature, will form in a shape such that the non-uniform energy convected to it is locally balanced by conduction into the solid. The interface shape is of interest relative to the crystal structure formed during solidification; regulating the crystal structure has application in casting naturally strengthened metallic composites. The results also pertain to phase-change energy storage devices, where the solidified configuration and overall heat transfer are needed. The analysis uses a conformal mapping technique to relate the desired interface coordinates to the components of the temperature gradient at the interface. These components are unknown because the interface shape is unknown. A Cauchy integral formulation provides a second relation involving the components, and a simultaneous solution yields the interface shape.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Heat and Mass Transfer; 25; July 198
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  • 11
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    Calculation of radiation from argon shock layers (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The accuracy of calculations of the radiation emissions from argon plasmas produced by the shock layers over blunt bodies is assessed. The existing theoretical and experimental spectroscopic data on argon are collated. A set of such data is selected for use in the radiative transfer calculations. Calculations are performed for the stagnation regions of the shock layers over laboratory-sized models using these data, and the results are compared with the existing experimental results obtained in a shock-tube. Through this comparison and a parametric study it is shown that radiative heat fluxes at the stagnation point in an argon environment can be calculated within an uncertainty of about 15%. It is shown also that radiative heat fluxes of the order of 100 kW/sq cm can be produced in the existing laboratory facilities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Quantitative Spectroscopy and Radiative Transfer; 28; July 198
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  • 12
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    Resonant entrainment of a confined pulsed jet (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper reports the discovery of a new resonant entrainment phenomenon associated with a confined, pulsed jet flow. It was found that a confined jet, when pulsed at an organ-pipe resonant frequency of the confinement tube, experiences greatly enhanced entrainment and mixing near the exit end of the confinement tube compared to a steady confined jet. The mixing and entrainment rates for the resonantly pulsed confined jet approach, and in some cases slightly exceed, those for an unconfined pulsed jet. Both visual and quantitative evidence of this phenomenon is presented. The new effect should be of considerable interest in ejector and combustor design, both of which benefit from any enhancement in mixing between a primary and a secondary flow
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 13
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    Use of thermocapillary migration in a controllable heat valve (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: In accordance with the Marangoni effect, immiscible droplets in a host fluid in which a temperature gradient exists move in the direction of increasing temperature. It is proposed that this thermocapillary migration could be used to construct a 'liquid wick' that would return the condensed vapor at the condenser end of a heat pipe back to the evaporator, thus completing the fluid circuit. The droplets would be formed by capillary pressure forcing the condensate through a perforated diaphragm whose temperature would control the droplet flux, and hence the heat flux between the two ends of the heat pipe, thus making it a controllable heat valve.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Applied Physics; 53; Dec. 198
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  • 14
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    Determination of boundary shape of cooled porous region (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The shape of a cooled porous wall section is found that will provide a uniform surface temperature, as dictated by material limitations, when the surface is subjected to spatially nonuniform heating. In the analysis, local temperatures and pressures in the porous material are expressed in terms of a potential function. From the imposed thermal conditions, this potential function is governed by the dual constraints of both its value and its normal derivative being specified along the heated surface. The unknown shape of this surface is obtained by meeting these dual conditions. The analytical method uses a generalized conformal mapping procedure that includes a curved boundary. The coolant flow can be compressible or incompressible, and its viscosity can depend on temperature.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 15
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    Spouts in a bed of silica powder associated with fluidization by outgassing of adsorbed water (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: International Journal of Multiphase Flow; 8; 4, 19; 1982
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  • 16
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    On current aspects of finite element computational fluid mechanics for turbulent flows (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A set of nonlinear partial differential equations suitable for the description of a class of turbulent three-dimensional flow fields in select geometries is identified. On the basis of the concept of enforcing a penalty constraint to ensure accurate accounting of ordering effects, a finite element numerical solution algorithm is established for the equation set and the theoretical aspects of accuracy, convergence and stability are identified and quantized. Hypermatrix constructions are used to formulate the reduction of the computational aspects of the theory to practice. The robustness of the algorithm, and the computer program embodiment, have been verified for pertinent flow configurations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 17
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    An analytical approach to thermal modeling of Bridgman-type crystal growth. I - One-dimensional analysis (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A relatively simple one-dimensional thermal model of the Bridgman growth process has been developed which is applicable to the growth of small diameter samples with conductivities similar to those of metallic alloys. The heat flow in a translating rod is analyzed in a way that is applicable to Biot numbers less than unity. The model accommodates an adiabatic zone, different heat transfer coefficients in the hot and cold zones, and changes in sample material properties associated with phase change. The analysis is applied to several simplified cases. The effect of the rod's motion is studied in a three-zone furnace for a rod sufficiently long that end effects can be neglected; end effects are then investigated for a motionless rod. Finally, the addition of a fourth zone, an independently controlled booster heater between the main heater and the adiabatic zone, is evaluated for its ability to increase the gradient in the sample at the melt interface and to control the position of the interface.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Crystal Growth; 58; 1982
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  • 18
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    Curved ducts with strong secondary motion - Velocity measurements of developing laminar and turbulent flow (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Two orthogonal components of velocity and associated Reynolds stresses are determined in a square-sectioned, 90 degree bend of 2.3 radius ratio by utilizing laser-Doppler velocimetry for Reynolds numbers of 790 and 40,000. Results show that boundary layers at the bend inlet of 0.25 and 0.15 of the hydraulic diameter create secondary velocity maxima of 0.6 and 0.4 of the bulk flow velocity, respectively. It is concluded that the boundary layer thickness is important to the flow development, mainly in the first half of the bend, especially when it is reduced to 0.15 of the hydraulic diameter. Smaller secondary velocities are found for turbulent flow in an identical duct with a radius ratio of 7.0 than in the strongly curved bend, although their effect is more important to the streamwise flow development because of the smaller pressure gradients. In addition, the detail and accuracy of the measurements make them suitable for evaluation of numerical techniques and turbulence models.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 19
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    Numerical solutions for the spin-up of a stratified fluid (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The model of Warn-Varnas et al. (1978) is used to numerically examine the spin-up flow of a thermally stratified fluid in a cylinder with an insulating side wall, and comparison of the results with the laser-Doppler measurements of Lee (1975) shows excellent agreement. It is shown that flow gradients are created in the interior of the fluid during the meridional circulation spin-up phase, and that the azimuthal flow decayed faster than has been predicted by Wallin (1969). It is established that viscous diffusion in the interior, arising from the interior-flow gradients, is the cause of the discrepancy with Wallin's theory.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Fluid Mechanics; 117; Apr. 198
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  • 20
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    Topology of three-dimensional separated flows (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A Legendre formulation for a pattern of streamlines adjacent to a surface considered as trajectories with properties consistent with those of a constant vector field is used to develop a mathematical framework for three-dimensional separated flows. Convergence of skin-friction lines onto a particular skin-friction line originating from a particular saddle point is defined as a necessary condition for flow separation. Steady, three-dimensional flow is considered, and singular points occurring in the skin-friction lines are shown to happen where the skin friction or the surface vorticity become zero, and become nodal or saddle points. The separation initiates and continues only globally, as a mixture of an infinite set of friction lines, or locally, with one line. The topography of streamlines in two-dimensional sections of three-dimensional flows is discussed, and examples are provided of a round-nosed body of revolution at varying angles of attack.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 21
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    Heat transfer from combustion gases to a single row of closely spaced tubes in a swirl crossflow Stirling engine heater (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: This paper describes an experimental program to determine the heat-transfer characteristics of a combustor and heat-exchanger system in a hybrid solar receiver which utilizes a Stirling engine. The system consists of a swirl combustor with a crossflow heat exchanger composed of a single row of 48 closely spaced curved tubes. In the present study, heat-transfer characteristics of the combustor/heat-exchanger system without a Stirling engine have been studied over a range of operating conditions and output levels using water as the working fluid. Nondimensional heat-transfer coefficients based on total heat transfer have been obtained and are compared with available literature data. The results show significantly enhanced heat transfer for the present geometry and test conditions. Also, heat transfer along the length of the tubes is found to vary, the effect depending upon test condition.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 22
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    The dependence of the shape and stability of captive rotating drops on multiple parameters (1982)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Asymptotic and numerical techniques in bifurcation theory are applied to the Young-Laplace equation governing meniscus shape in order to analyze the dependence of the shape and stability of rigidly rotating drops held captive between corotating solid faces on multiple parameters. Asymptotic analysis of the evolution of drop shape from the cylindrical as a function of distance between the solid faces, drop volume, rotational Bond number and gravitational Bond number shows that some shape bifurcations from cylinders to wavy, axisymmetric menisci are ruptured by small changes in drop volume or gravity. Computer calculations of axisymmetric drop shapes based on a finite element representation of the interface and numerical algorithms for tracking shape families and singular points are then used to map drop stability for the four-dimensional parameter space. The results of the asymptotic and numerical analyses are shown to agree well within the limited range of parameters where the asymptotic analysis is valid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Philosophical Transactions, Series A (ISSN 0080-4614); 306; 1493,; Aug. 27
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  • 23
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    ADI on staggered mesh - A method for the calculation of compressible convection (1982)
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    Publication Date: 2011-08-18
    Description: An alternating direction implicit (ADI) method has been applied to a staggered grid for the computation of convection in a highly stratified fluid. Since artificial viscosity is not needed, subtle effects like the onset of convection can be studied. These computations compare well with the 2-D results by Graham (1975) and also agree with standard Boussinesq results when taken to that limit. Good efficiency has been achieved with a time step hundreds of times larger than the stability limit imposed by the explicit treatment of diffusion and the Courant number is not restricted to be below 1. The Navier-Stokes equation contains cross spatial derivatives which are treated explicitly in most ADI schemes. The destabilizing effect of such a practice on a 2-D model system with second-order spatial derivative terms only was analyzed and found to be not excessive.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 47; July 198
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  • 24
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    A high-resolution numerical technique for inviscid gas-dynamic problems with weak solutions (1982)
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    Publication Date: 2011-08-18
    Description: The shock resolution of Harten's (1982) second-order explicit method for one-dimensional hyperbolic conservation laws is investigated for a two-dimensional gas-dynamic problem. The possible extension to a high resolution implicit method for both one- and two-dimensional problems is also investigated. Applications of Harten's method to the quasi-one-dimensional nozzle problem with two nozzle shapes (divergent and convergent-divergent) and the two-dimensional shock-reflection problem resulted in high shock resolution steady-state numerical solutions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 25
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    Numerical solution of viscous flow in unbounded fluid (1982)
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    Publication Date: 2011-08-18
    Description: Incompressible viscous flow fields induced by initial vorticity distributions with bounded support or exponential decay in the far field are investigated. A numerical scheme for the solution of the vorticity distribution and the velocity field is presented with special emphasis on the treatment of the boundary data. The efficiency of the scheme is demonstrated. The present method has been applied to the study of the merging and collision of vortex rings.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 26
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    Simulation of large turbulent vortex structures with the parabolic Navier-Stokes equations (1982)
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    Publication Date: 2011-08-18
    Description: The theoretical basis for well posed marching of a Parabolic Navier-Stokes (PNS) computational technique for supersonic flow is discussed and examples given to verify the analysis. It is demonstrated that stable computations can be made even with very small steps in the marching direction. The method is applied to cones at large angle of attack in high Reynolds number, supersonic flow. Streamline trajectories generated from the numerical solutions demonstrate the development of vortex structures of the lee side of the cone. Previously announced in STAR as N83-22551
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  • 27
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    Relaxation solution of the full Euler equations (1982)
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    Publication Date: 2011-08-18
    Description: A numerical procedure for the relaxation solution of the full steady Euler equations is described. By embedding the Euler system in a second order surrogate system, central differencing may be used in subsonic regions while retaining matrix forms well suited to iterative solution procedures and convergence acceleration techniques. Hence, this method allows the development of stable, fully conservative differencing schemes for the solution of quite general inviscid flow problems. Results are presented for both subcritical and shocked supercritical internal flows. Comparisons are made with a standard time dependent solution algorithm. Previously announced in STAR as N82-24859
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  • 28
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    Pointwise and scanning laser anemometer measurements in steady and unsteady separated turbulent boundary layers (1982)
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    Publication Date: 2011-08-18
    Description: The physical features of steady and unsteady freestream separating turbulent boundary layers that have been determined by pointwise laser anemometer measurements are outlined. It is seen that the large-scale structures control the outer region's backflow behavior. Near the wall, the mean backflow velocity profile for both the steady and unsteady cases is found to scale on the maximum negative mean velocity and its distance from the wall. A description is given of a scanning laser anemometer that produces nearly instantaneous velocity profiles for examing the temporal features of these large-scale structures. Also described is a 'zero-wake' seeder that supplies particles to the outer shear layer and freestream flow with a minimal disturbance.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 29
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    A new numerical method for the simulation of three-dimensional flow in a pipe (1982)
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    Publication Date: 2011-08-18
    Description: A new numerical technique for simulating three dimensional, unsteady, incompressible pipe flows is presented and its utility and accuracy is shown. Each vector function in the expansion of the velocity field is divergence free and satisfies the boundary conditions for viscous flow. Some of the benefits of the expansion technique are that pressure is eliminated from the dynamics, only two unknowns per mesh point are required, implicit treatment of the viscous terms is provided at no extra computational cost, and no fractional time steps are required. The method uses spectral expansions: Fourier series in the azimuthal and streamwise directions, and Jacobi polynominals in the radial direction. Previously announced in STAR as N82-31644
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  • 30
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    Numerical simulation of wall-bounded turbulent shear flows (1982)
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    Publication Date: 2011-08-18
    Description: Developments in three dimensional, time dependent numerical simulation of turbulent flows bounded by a wall are reviewed. Both direct and large eddy simulation techniques are considered within the same computational framework. The computational spatial grid requirements as dictated by the known structure of turbulent boundary layers are presented. The numerical methods currently in use are reviewed and some of the features of these algorithms, including spatial differencing and accuracy, time advancement, and data management are discussed. A selection of the results of the recent calculations of turbulent channel flow, including the effects of system rotation and transpiration on the flow are included. Previously announced in STAR as N82-28577
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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    An evaluation of superminicomputers for thermal analysis (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The use of superminicomputers for solving a series of increasingly complex thermal analysis problems is investigated. The approach involved (1) installation and verification of the SPAR thermal analyzer software on superminicomputers at Langley Research Center and Goddard Space Flight Center, (2) solution of six increasingly complex thermal problems on this equipment, and (3) comparison of solution (accuracy, CPU time, turnaround time, and cost) with solutions on large mainframe computers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 437-451
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    Effects of rotation and magnetic field on the onset of convective instability in a liquid layer due to buoyancy and surface tension (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Thermocapillary stability characteristics of a horizontal liquid layer heated from below rotating about a vertical axis and subjected to a uniform vertical magnetic field are analyzed under a variety of thermal and electromagnetic boundary conditions. Results based on analytical solutions to the pertinent eigenvalue problems are discussed in the light of earlier work on special cases of the more general problem considered here to show in particular the effects of the heat transfer, nonzero curvature and gravity waves at the two-fluid interface. Although the expected stabilizing action of the Coriolis and Lorentz force fields in this configuration are in evidence the optimal choice of an appropriate range for the relevant parameters is shown to be critically dependent on the interfacial effects mentioned above.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 366-373
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    The geophysical importance of bubbles in the sea (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Present knowledge of the mechanisms for production and enrichment and film drops by bursting bubbles is summarized, with particular emphasis on the unsolved problems. Sea salt is by far the major constituent cycled through the Earth's atmosphere each year. Bursting bubbles in the oceans appear to be primarily responsible. These salt particles play a role in the formation of maritime clouds, which in turn affect the Earth's radiation budget. Along with the salt are carried various chemical pollutants and potentially pathogenic microorganisms, often in highly enriched form.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 255-259
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    Raindrop oscillations (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A model of the change in shape of a raindrop is presented. Raindrops measured by two orthogonal cameras were classified by shape and orientation to determine the nature of the oscillation. A physical model based on potential energy was then developed to study the amplitude variation of oscillating drops. The model results show that oscillations occur about the equilibrium axis ratio, but the time average axis ratio if significantly more spherical for large amplitudes because of asymmetry in the surface potential energy. A generalization of the model to oscillations produced by turbulence yields average axis ratios that are consistent with the camera measurements. The model results for average axis ratios were applied to rainfall studies with a dual polarized radar.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 244-246
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    A wind tunnel investigation of the shape of uncharged raindrops in the presence of an external, electric field (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Results of a wind tunnel experiment in which electrically uncharged water drops of 500 to 3000 microns equivalent radius are freely suspended in the vertical air stream of the UCLA cloud tunnel are presented. During this suspension the drops were exposed to external vertical electric fields of 500 to 8,000 volts/cm. The change in drop shape with drop size and electric field strength was noted and is discussed in the light of theoretical work cited in the literature which unfortunately does not take into account the effects of air flow past the drop. The wind tunnel study is documented by stills from a 16 mm film record that demonstrates the shape of water drops in response to both hydrodynamic and electric forces.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 239-243
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  • 36
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    Bubble shapes in steady axisymmetric flows at intermediate Reynolds number (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The shape of a gas bubble which rises through a quiescent incompressible, Newtonian fluid at intermediate Reynolds numbers is considered. Exact numerical solutions for the velocity and pressure fields, as well as the bubble shape, are obtained using finite difference techniques and a numerically generated transformation to an orthogonal, boundary-fitted coordinate system. No restriction is placed on the allowable magnitude of deformation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 151-156
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    Holographic studies of the vapor explosion of vaporizing water-in-fuel emulsion droplets (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Holographic studies were performed which examined the fragmentation process during vapor explosion of a water-in-fuel (hexadecane/water) emulsion droplet. Holograms were taken at 700 to 1000 microseconds after the vapor explosion. Photographs of the reconstructed holograms reveal a wide range of fragment droplet sizes created during the explosion process. Fragment droplet diameters range from below 10 microns to over 100 microns. It is estimated that between ten thousand and a million fragment droplets can result from this extremely violent vapor explosion process. This enhanced atomization is thus expected to have a pronounced effect on vaporization processes which are present during combustion of emulsified fuels.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 112-119
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    Behavior of liquid hydrogen inside an ICF target (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The configuration of liquid hydrogen inside spherical glass shell ICF target was studied both theoretically and experimentally. Because of the zero contact angle between the .D2 liquid and glass substrate and the limited wetting surface that is continuous, the liquid hydrogen completely covers the interior of the glass shell, resulting in the formation of a void at the center. For this reason, the present problem distinguishes itself from that for a sessile drop sitting on a flat surface. A theory was formulated to calculate the liquid hydrogen configuration by including the London-dispersion force between the liquid and the substrate molecules. The net result is an augmented Bashforth-Adams equation appropriate to a spherical substrate, which is considered to be the major contribution of the present work. Preliminary calculations indicate that this equation accurately models the liquid hydrogen behavior inside a spherical microshell.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 96-106
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  • 39
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    NASTRAN thermal analyzer in a unified finite-element treatment of thermo-structural analyses (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The NASTRAN thermal analyzer (NTA) which performs large-scale unified thermo-structural analyses with the NASTRAN (NASA structural analysis) computer program is described. The mathematical similitude between these two distinct disciplines of thermal and structure is examined. It serves as the theoretical basis upon which the implementation of the thermal capability in NASTRAN was accomplished. The program structure, the functional flow, the solution algorithms, the organization of an input data deck and the solution capabilities of NTA are summarized. Emphasis is placed on the interface of the unified approach in thermo-structural analyses where stresses, deflections, vibrations and bucklings induced by the effect of temperature change are of concern. Attentions are also directed to the preprocessor and post processors. As a specially designed preprocessor, the VIEW program is capable of generating exchange factors which can be output, at user's option, in formats compatible with that required by NTA. Two post processors that serve specific objectives are included. They are the thermal variance analysis and the graphical displaying capability of temperatures in color or black and white.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 1-22
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    Profiles of electrified drops and bubbles (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Axisymmetric equilibrium shapes of conducting drops and bubbles, (1) pendant or sessile on one face of a circular parallel-plate capacitor or (2) free and surface-charged, are found by solving simultaneously the free boundary problem consisting of the augmented Young-Laplace equation for surface shape and the Laplace equation for electrostatic field, given the surface potential. The problem is nonlinear and the method is a finite element algorithm employing Newton iteration, a modified frontal solver, and triangular as well as quadrilateral tessellations of the domain exterior to the drop in order to facilitate refined analysis of sharply curved drop tips seen in experiments. The stability limit predicted by this computer-aided theoretical analysis agrees well with experiments.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 322-329
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    Asymptotic Expansions and Estimates for the Capillary Problem (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The asymptotic properties for the small Bond number B of the equilibrium capillary interface interior to a circular cylindrical tube vertically dipped in an infinite reservoir of liquid are discussed. (The Bond number B is a dimensionless parameter which is the ratio of gravitational to capillary forces.) The formal expansion in powers of B of the solution to the differential equation describing the equilibrium surface (as can be obtained by standard perturbation methods) is proved to be truly asymptotic -- to all orders and uniformly in the variable and parameter gamma, the contact angle. Sequences of general estimates, in closed form, from above and from below, are also given for the solution and related functions. The M-th term in these sequences are asymptotically exact to order m. An idiosyncrasy of the problem, crucial in obtaining these estimates, is the absolute monotonicity of the structural function of the system in integral form.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 344-349
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    Fluid dynamical description of relativistic nuclear collisions (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: On the basis of both a conventional relativistic nuclear fluid dynamic model and a two fluid generalization that takes into account the interpenetration of the target and projectile upon contact, collisions between heavy nuclei moving at relativistic speeds are calculated. This is done by solving the relevant equations of motion numerically in three spatial dimensions by use of particle in cell finite difference computing techniques. The effect of incorporating a density isomer, or quasistable state, in the nuclear equation of state at three times normal nuclear density, and the effect of doubling the nuclear compressibility coefficient are studied. For the reaction 20Ne + 238U at a laboratory bombarding energy per nucleon of 393 MeV, the calculated distributions in energy and angle of outgoing charged particles are compared with recent experimental data both integrated over all impact parameters and for nearly central collisions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 260-267
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    Capillary surface discontinuities above reentrant corners (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A particular configuration of a vertical capillary tube for which S is the equilibrium interface between two fluids in the presence of a downward pointing gravitational field was investigated. S is the graph a function u whose domain is the (horizontal) cross section gamma of the tube. The mean curvature of S is proportional to its height above a fixed reference plane and lambda is a prescribed constant and may be taken between zero and pi/2. Domains gamma for which us is a bounded function but does not extend continuously to d gamma are sought. Simple domains are found and the behavior of u in those domains is studied. An important comparison principle that has been used in the literature to derive many of the results in capillarity is reviewed. It allows one to deduce the approximate shape of a capillary surface by constructing comparison surfaces with mean curvature and contact angle close to those of the (unknown) solution surface. In the context of nonparametric problems the comparison principle leads to height estimates above and below for the function u. An example from the literature where these height estimates have been used successfully is described. The promised domains for which the bounded u does not extend continuously to the boundary are constructed. The point on the boundary at which u has a jump discontinuity will be the vertext of a re-entrant corner having any interior angle theta pi. Using the comparison principle the behavior of u near this point is studied.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 295-302
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    Drop rebound in clouds and precipitation (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The possibility of rebound for colliding cloud drops was measured by determining the collection efficiency. The collection efficiency for 17 size pairs of relatively uncharged drops in over 500 experimental runs was measured using two techniques. The collection efficiencies fall in a narrow range of 0.60 to 0.70 even though the collection drop was varied between 63 and 326 microns and the size ratio from 0.05 to 0.33. In addition the measured values of collection efficiencies (Epsilon) were below the computed values of collision efficiencies (E) for rigid spheres. Therefore it was concluded that rebound was occurring for these sizes since inferred coalescence (epsilon = Epsilon/E) efficiencies are about 0.6 yo 0.8. At a very small size ratio (r/R = p = 0.05, R = 326 microns) the coalescence efficiency inferred is in good agreement with the experimental findings for a supported collector drop. At somewhat large size ratios the inferred values of epsilon are well above results of supported drop experiments, but show a slight correspondence in collected drop size dependency to two models of drop rebound. At a large size ratio (p = 0.73, R = 275) the inferred coalescence efficiency is significantly different from all previous results.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 247-254
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    Resonances, radiation pressure and optical scattering phenomena of drops and bubbles (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Acoustic levitation and the response of fluid spheres to spherical harmonic projections of the radiation pressure are described. Simplified discussions of the projections are given. A relationship between the tangential radiation stress and the Konstantinov effect is introduced and fundamental streaming patterns for drops are predicted. Experiments on the forced shape oscillation of drops are described and photographs of drop fission are displayed. Photographs of critical angle and glory scattering by bubbles and rainbow scattering by drops are displayed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 166-174
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    Droplets Generated from a new OGEE shaped, liquid, air-shear, electrostatic nozzle (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A series of experimental tests was carried out on an 'OGEE' shaped planform, liquid air-shear electrostatic nozzle. Liquid was ejected from the upper surface of the nozzle and was then dispersed and atomized efficiently by a high speed air flow passing over the nozzle and by the effect of two very strong coherent air vortices generated by the 'OGEE' shaped nozzle surface. Initial test results which are presented show the nozzle to perform far superior to a similar delta wing shaped design which is used extensively in various industries applications.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 120-123
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    An experimental investigation of circulation control flow fields using holographic interferometry (1982)
    In:  CASI
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    Publication Date: 2019-06-28
    Description: Experiments are presented which were conducted on flow fields produced by a circulation control airfoil utilizing the Coanda effect at the trailing edge. The application of holographic interferometry to obtain both visualization and quantitative data on the flow field about a circulation control airfoil at transonic flow speed is covered. A brief description of the flow model and measurement techniques is given. The data reduction procedure, results, and interpretation are presented. The results have provided a good deal of information on the character of the flow field, particularly in the neighborhood of the trailing edge. As to the airfoil design, it is apparent that improved performance can be achieved if jet detachment is delayed. Another design improvement would involve the development of an optimum trailing-edge shape for the expected operating Mach and Reynolds number ranges.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA-CR-166482 , NAS 1.26:166482
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    Thermal radiation view factor: Methods, accuracy and computer-aided procedures (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The computer aided thermal analysis programs which predicts the result of predetermined acceptable temperature range prior to stationing of these orbiting equipment in various attitudes with respect to the Sun and the Earth was examined. Complexity of the surface geometries suggests the use of numerical schemes for the determination of these viewfactors. Basic definitions and standard methods which form the basis for various digital computer methods and various numerical methods are presented. The physical model and the mathematical methods on which a number of available programs are built are summarized. The strength and the weaknesses of the methods employed, the accuracy of the calculations and the time required for computations are evaluated. The situations where accuracies are important for energy calculations are identified and methods to save computational times are proposed. Guide to best use of the available programs at several centers and the future choices for efficient use of digital computers are included in the recommendations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 58 p
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    Some aspects of algorithm performance and modeling in transient thermal analysis of structures (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The status of an effort to increase the efficiency of calculating transient temperature fields in complex aerospace vehicle structures is described. The advantages and disadvantages of explicit and implicit algorithms are discussed. A promising set of implicit algorithms with variable time steps, known as the GEAR package is described. Four test problems, used for evaluating and comparing various algorithms, were selected and finite element models of the configurations are described. These problems include a space shuttle frame component, an insulated cylinder, a metallic panel for a thermal protection system, and a model of the space shuttle orbiter wing. Results generally indicate a preference for implicit oer explicit algorithms for solution of transient structural heat transfer problems when the governing equations are stiff.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 91-98
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    A method to model latent heat for transient analysis using NASTRAN (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A sample heat transfer analysis is demonstrated which includes the heat of fusion. The method can be used to analyze a system with nonconstant specific heat. The enthalpy is introduced as an independent degree of freedom at each node. The user input consists of a curve of temperature as a function of enthalpy, which may include a constant temperature phase change. The basic NASTRAN heat transfer capability is used to model the effects of latent heat with existing direct matrix output and nonlinear load data cards. Although some user care is required, the numerical stability of the integration is quite good when the given recommendations are followed. The theoretical equations used and the NASTRAN techniques are shown.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 83-89
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    Studies of the nucler equation of state using numerical calculations of nuclear drop collisions (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A numerical calculation for the full thermal dynamics of colliding nuclei was developed. Preliminary results are reported for the thermal fluid dynamics in such processes as Coulomb scattering, fusion, fusion-fission, bulk oscillations, compression with heating, and collisions of heated nuclei.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 268-279
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    Recent developments in thermal radiation system analyzer (Trasys) (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Changes in the thermal radiation analyzer system (TRASYS) computer program are discussed. New capabilities were added while keeping intact the same data input structure. An overview of the program structure and general capabilities is given. Where appropriate, assessments are made of new features. The application of TRASYS peripheral programs and the importance they have in developing a totally integrated thermal analysis system are discussed. Form factor computations times were reduced approximately 40 percent, and the longer flux runs were reduced 50 percent when shadow tables were used.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 234-251
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    Reentry heat transfer analysis of the space shuttle orbiter (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A structural performance and resizing finite element thermal analysis computer program was used in the reentry heat transfer analysis of the space shuttle. Two typical wing cross sections and a midfuselage cross section were selected for the analysis. The surface heat inputs to the thermal models were obtained from aerodynamic heating analyses, which assumed a purely turbulent boundary layer, a purely laminar boundary layer, separated flow, and transition from laminar to turbulent flow. The effect of internal radiation was found to be quite significant. With the effect of the internal radiation considered, the wing lower skin temperature became about 39 C (70 F) lower. The results were compared with fight data for space transportation system, trajectory 1. The calculated and measured temperatures compared well for the wing if laminar flow was assumed for the lower surface and bay one upper surface and if separated flow was assumed for the upper surfaces of bays other than bay one. For the fuselage, good agreement between the calculated and measured data was obtained if laminar flow was assumed for the bottom surface. The structural temperatures were found to reach their peak values shortly before touchdown. In addition, the finite element solutions were compared with those obtained from the conventional finite difference solutions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 295-325
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    The SPAR thermal analyzer: Present and future (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The SPAR thermal analyzer, a system of finite-element processors for performing steady-state and transient thermal analyses, is described. The processors communicate with each other through the SPAR random access data base. As each processor is executed, all pertinent source data is extracted from the data base and results are stored in the data base. Steady state temperature distributions are determined by a direct solution method for linear problems and a modified Newton-Raphson method for nonlinear problems. An explicit and several implicit methods are available for the solution of transient heat transfer problems. Finite element plotting capability is available for model checkout and verification.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 35-50
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    The numerical analysis of the rotational theory for the formation of lunar globules (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The morphology of lunar globules is studied through the application of a numerical analysis of their rotation in space during cooling. It is assumed that molten rock is shot from the surface of the moon, solidifies in space above the moon and then falls back to the surface. The rotational theory studied makes the following assumptions: the volume of the molten rock does not change during cooling; the angular momentum is conserved; there are no internal motions because of the high viscosity of the molten rock, i.e., in equilibrium the globule is rotating as a rigid body; finally, the kinetic reaction of the globule to the forces is fast relative to the rate of cooling, i.e., the globule reaches equilibrium at constant energy. These assumptions are subjected to numerical analysis yielding good agreement between the actual globule shapes and the numerical results, but leaving some doubt as to the validity of the rotational theory due to the failure to establish the existence of true local minima and an incomplete understanding of the thermokentics.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 350-357
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    Fluid models and simulations of biological cell phenomena (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The dynamics of coated droplets are examined within the context of biofluids. Of specific interest is the manner in which the shape of a droplet, the motion within it as well as that of aggregates of droplets can be controlled by the modulation of surface properties and the extent to which such fluid phenomena are an intrinsic part of cellular processes. From the standpoint of biology, an objective is to elucidate some of the general dynamical features that affect the disposition of an entire cell, cell colonies and tissues. Conventionally averaged field variables of continuum mechanics are used to describe the overall global effects which result from the myriad of small scale molecular interactions. An attempt is made to establish cause and effect relationships from correct dynamical laws of motion rather than by what may have been unnecessary invocation of metabolic or life processes. Several topics are discussed where there are strong analogies droplets and cells including: encapsulated droplets/cell membranes; droplet shape/cell shape; adhesion and spread of a droplet/cell motility and adhesion; and oams and multiphase flows/cell aggregates and tissues. Evidence is presented to show that certain concepts of continuum theory such as suface tension, surface free energy, contact angle, bending moments, etc. are relevant and applicable to the study of cell biology.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 303-307
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    A numerical method for integrating the kinetic equations of droplet spectra evolution by condensation/evaporation and by coalescence/breakup processes (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An extension of the method of moments is developed for the numerical integration of the kinetic equations of droplet spectra evolution by condensation/evaporation and by coalescence/breakup processes. The number density function n sub k (x,t) in each separate droplet packet between droplet mass grid points (x sub k, x sub k+1) is represented by an expansion in orthogonal polynomials with a given weighting function. In this way droplet number concentrations, liquid water contents and other moments in each droplet packet are conserved and the problem of solving the kinetic equations is replaced by one of solving a set of coupled differential equations for the number density function moments. The method is tested against analytic solutions of the corresponding kinetic equations. Numerical results are obtained for different coalescence/breakup and condensation/evaporation kernels and for different initial droplet spectra. Also droplet mass grid intervals, weighting functions, and time steps are varied.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 330-335
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    A new droplet generator (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A new droplet generator is described. A loud speaker driven extractor needle was immersed in a pendant drop. Pulsing the speaker extracted the needle forming a fluid ligament which will decay into a droplet. The droplets were sized by stroboscopic photographs. The droplet's size was changed by varying the amplitude of the speaker pulses and the extractor needle diameter. The mechanism of droplet formation is discussed and photographs of ligament decay are presented. The droplet generator worked well on both oil and water based pesticide formulations. Current applications and results are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 195-202
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    Non-axisymmetric shapes of a rotating drop in an immiscible system (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The nonaxisymmetric shapes of a rotating drop in an immiscible system were studied. Five basic families of shapes (axisymmetric, two-lobed, three-lobed, four-lobed, and toroidal) were observed. The sequence (axisymmetric to two-lobed to three-lobed to four-lobed to toroidal) seems to be linked to increasing spin-up velocity. For the axisymmetric case, direct comparisons of experiments with the theory of a free rotating drop were surprisingly good the equatorial area differs from theory by only 30%. Furthermore, the non-axisymmetric shapes are in good qualitative agreement with the theory, although the theory does not address the presence of an outer fluid.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 203-213
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    A numerical method for the dynamics of non-spherical cavitation bubbles (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A boundary integral numerical method for the dynamics of nonspherical cavitation bubbles in inviscid incompressible liquids is described. Only surface values of the velocity potential and its first derivatives are involved. The problem of solving the Laplace equation in the entire domain occupied by the liquid is thus avoided. The collapse of a bubble in the vicinity of a solid wall and the collapse of three bubbles with collinear centers are considered.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 175-181
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    Experimental study of time-dependent flows in laboratory atmospheric flow models (1982)
    In:  Other Sources
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    Publication Date: 2016-06-07
    Description: Baroclinic waves in a rotating, differentially-heated annulus of liquid were studied in support of the Atmospheric General Circulation Experiment. Specific objectives were to determine: (1) the nature of the flow at shallow depths, (2) the effect of a rigid lid vs. free surface, and (3) the nature of fluctuations in the waves as a function of rotation rate, depth, and type of surface. It is found that flows with a rigid lid are basically the same as those with a free surface, except for a decrease in flow rate. At shallow depths steady flows are found in essentially the same form, but the incidence of unsteady flows is greatly diminished.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Marshall Space Flight Center The 1982 NASA(ASEE Summer Fac. Fellowship Program; 22 p
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    Transient thermal analysis of a titanium multiwall thermal protection system (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The application of the SPAR thermal analyzer to the thermal analysis of a thermal protection system concept is discussed. The titanium multiwall thermal protection system concept consists of alternate flat and dimpled sheets which are joined together at the crests of the dimples and formed into 30 cm by 30 cm (12 in. by 12 in.) tiles. The tiles are mechanically attached to the structure. The complex tile geometry complicates thermal analysis. Three modes of heat transfer were considered: conduction through the gas inside the tile, conduction through the metal, and radiation between the various layers. The voids between the dimpled and flat sheets were designed to be small enough so that natural convection is insignificant (e.g., Grashof number 1000). A two step approach was used in the thermal analysis of the multiwall thermal protection system. First, an effective normal (through-the-thickness) thermal conductivity was obtained from a steady state analysis using a detailed SPAR finite element model of a small symmetric section of the multiwall tile. This effective conductivity was then used in simple one dimensional finite element models for preliminary analysis of several transient heat transfer problems.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 349-361
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    Guidelines for developing vectorizable computer programs (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Some fundamental principles for developing computer programs which are compatible with array-oriented computers are presented. The emphasis is on basic techniques for structuring computer codes which are applicable in FORTRAN and do not require a special programming language or exact a significant penalty on a scalar computer. Researchers who are using numerical techniques to solve problems in engineering can apply these basic principles and thus develop transportable computer programs (in FORTRAN) which contain much vectorizable code. The vector architecture of the ASC is discussed so that the requirements of array processing can be better appreciated. The "vectorization" of a finite-difference viscous shock-layer code is used as an example to illustrate the benefits and some of the difficulties involved. Increases in computing speed with vectorization are illustrated with results from the viscous shock-layer code and from a finite-element shock tube code. The applicability of these principles was substantiated through running programs on other computers with array-associated computing characteristics, such as the Hewlett-Packard (H-P) 1000-F.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 393-403
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    Reentry heating analysis of space shuttle with comparison of flight data (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Surface heating rates and surface temperatures for a space shuttle reentry profile were calculated for two wing cross sections and one fuselage cross section. Heating rates and temperatures at 12 locations on the wing and 6 locations on the fuselage are presented. The heating on the lower wing was most severe, with peak temperatures reaching values of 1240 C for turbulent flow and 900 C for laminar flow. For the fuselage, the most severe heating occured on the lower glove surface where peak temperatures of 910 C and 700 C were calculated for turbulent flow and laminar flow, respectively. Aluminum structural temperatures were calculated using a finite difference thermal analyzer computer program, and the predicted temperatures are compared to measured flight data. Skin temperatures measured on the lower surface of the wing and bay 1 of the upper surface of the wing agreed best with temperatures calculated assuming laminar flow. The measured temperatures at bays two and four on the upper surface of the wing were in quite good agreement with the temperatures calculated assuming separated flow. The measured temperatures on the lower forward spar cap of bay four were in good agreement with values predicted assuming laminar flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 271-294
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    Role of IAC in large space systems thermal analysis (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Computer analysis programs to evaluate critical coupling effects that can significantly influence spacecraft system performance are described. These coupling effects arise from the varied parameters of the spacecraft systems, environments, and forcing functions associated with disciplines such as thermal, structures, and controls. Adverse effects can be expected to significantly impact system design aspects such as structural integrity, controllability, and mission performance. One such needed design analysis capability is a software system that can integrate individual discipline computer codes into a highly user-oriented/interactive-graphics-based analysis capability. The integrated analysis capability (IAC) system can be viewed as: a core framework system which serves as an integrating base whereby users can readily add desired analysis modules and as a self-contained interdisciplinary system analysis capability having a specific set of fully integrated multidisciplinary analysis programs that deal with the coupling of thermal, structures, controls, antenna radiation performance, and instrument optical performance disciplines.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 253-270
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    Space Shuttle orbiter entry heating and TPS response: STS-1 predictions and flight data (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Aerothermodynamic development flight test data from the first orbital flight test of the Space Transportation System (STS) transmitted after entry blackout is given. Engineering predictions of boundary layer transition and numerical simulations of the orbiter flow field were confirmed. The data tended to substantiate preflight predictions of surface catalysis phenomena. The thermal response of the thermal protection system was as expected. The only exception is that internal free convection was found to be significant in limiting the peak temperature of the structure in areas which do not have internal insulation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 327-347
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    A variational approach to the study of capillary phenomena (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The problem of determining the free surface of a liquid in a capillary tube, and of a liquid drop, sitting first on a horizontal plane and then on more general surfaces is considered. With some modifications, the method applies to the study of pendent drops and of rotating drops as well. The standard capillary problem, i.e. the determination of the free surface of a liquid in a thin tube of general cross section, which resuls from the simultaneous action of surface tension, boundary adhesion and gravity is discussed. It turns out that in this case the existence of the solution surface depends heavily on the validity of a simple geometric condition about the mean curvature of the boundary curve of the cross section of the capillary tube. Some particular examples of physical interest are also be discussed. Liquid drops sitting on or hanging from a fixed horizontal plane are discussed. The symmetry of the solutions (which can actually be proved, as consequence of a general symmetrization argument) now plays the chief role in deriving both the existence and the regularity of energy-minimizing configurations. When symmetry fails (this is the case, for example, when the contact angle between the drop and the plate is not constant, or when the supporting surface is not itself symmetric), then more sophisticated methods must be used. Extensions in this direction are outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 374-379
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    Mechanics of couple-stress fluid coatings (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The formal development of a theory of viscoelastic surface fluids with bending resistance - their kinematics, dynamics, and rheology are discussed. It is relevant to the mechanics of fluid drops and jets coated by a thin layer of immiscible fluid with rather general rheology. This approach unifies the hydrodynamics of two-dimensional fluids with the mechanics of an elastic shell in the spirit of a Cosserat continuum. There are three distinct facets to the formulation of surface continuum mechanics. Outlined are the important ideas and results associated with each: the kinematics of evolving surface geometries, the conservation laws governing the mechanics of surface continua, and the rheological equations of state governing the surface stress and moment tensors.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 380-383
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    Survey of computer programs for heat transfer analysis (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An overview is presented of the current capabilities of thirty-eight computer programs that can be used for solution of heat transfer problems. These programs range from the large, general-purpose codes with a broad spectrum of capabilities, large user community and comprehensive user support (e.g., ANSYS, MARC, MITAS 2 MSC/NASTRAN, SESAM-69/NV-615) to the small, special purpose codes with limited user community such as ANDES, NNTB, SAHARA, SSPTA, TACO, TEPSA AND TRUMP. The capabilities of the programs surveyed are listed in tabular form followed by a summary of the major features of each program. As with any survey of computer programs, the present one has the following limitations: (1) It is useful only in the initial selection of the programs which are most suitable for a particular application. The final selection of the program to be used should, however, be based on a detailed examination of the documentation and the literature about the program; (2) Since computer software continually changes, often at a rapid rate, some means must be found for updating this survey and maintaining some degree of currency.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 487-561
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    Development of a CRAY 1 version of the SINDA program (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The SINDA thermal analyzer program was transferred from the UNIVAC 1110 computer to a CYBER And then to a CRAY 1. Significant changes to the code of the program were required in order to execute efficiently on the CYBER and CRAY. The program was tested on the CRAY using a thermal math model of the shuttle which was too large to run on either the UNIVAC or CYBER. An effort was then begun to further modify the code of SINDA in order to make effective use of the vector capabilities of the CRAY.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 425-435
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    Evaluation of the SPAR thermal analyzer on the CYBER-203 computer (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The use of the CYBER 203 vector computer for thermal analysis is investigated. Strengths of the CYBER 203 include the ability to perform, in vector mode using a 64 bit word, 50 million floating point operations per second (MFLOPS) for addition and subtraction, 25 MFLOPS for multiplication and 12.5 MFLOPS for division. The speed of scalar operation is comparable to that of a CDC 7600 and is some 2 to 3 times faster than Langley's CYBER 175s. The CYBER 203 has 1,048,576 64-bit words of real memory with an 80 nanosecond (nsec) access time. Memory is bit addressable and provides single error correction, double error detection (SECDED) capability. The virtual memory capability handles data in either 512 or 65,536 word pages. The machine has 256 registers with a 40 nsec access time. The weaknesses of the CYBER 203 include the amount of vector operation overhead and some data storage limitations. In vector operations there is a considerable amount of time before a single result is produced so that vector calculation speed is slower than scalar operation for short vectors.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 405-424
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    Interactive computation of radiation view factors (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The development of a pair of computer programs to calculate the radiation exchange view factors is described. The surface generation program is based upon current graphics capabilities and includes special provisions which are unique to the radiation problem. The calculational program uses a combination of contour and double area integration to permit consideration of radiation with obstruction surfaces. Examples of the surface generation and the calculation are given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 221-241
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    Electrohydrodynamic (EHD) stimulation of jet breakup (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Electrohydrodynamic (EHD) excitation of liquid jets offers an alternative to piezoelectric excitation without the complex frequency response caused by piezoelectric and mechanical resonances. In an EHD exciter, an electrode near the nozzle applies an alternating Coulomb force to the jet surface, generating a disturbance which grows until a drop breaks off downstream. This interaction is modelled quite well by a linear, long wave model of the jet together with a cylindrical electric field. The breakup length, measured on a 33 micrometer jet, agrees quite well with that predicted by the theory, and increases with the square of the applied voltage, as expected. In addition, the frequency response is very smooth, with pronounced nulls occurring only at frequencies related to the time which the jet spends inside the exciter.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 63-70
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    Dielectrophoretic levitation of droplets and bubbles (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Uncharged droplets and bubbles can be levitated dielectrophoretically in liquids using strong, nonuniform electric fields. The general equations of motion for a droplet or bubble in an axisymmetric, divergence-free electrostatic field allow determination of the conditions necessary and sufficient for stable levitation. The design of dielectrophoretic (DEP) levitation electrode structures is simplified by a Taylor-series expansion of cusped axisymmetric electrostatic fields. Extensive experimental measurements on bubbles in insulating liquids verify the simple dielectrophoretic model. Other have extended dielectrophoretic levitation to very small particles in aqueous media. Applications of DEP levitation to the study of gas bubbles, liquid droplets, and solid particles are discussed. Some of these applications are of special interest in the reduced gravitational field of a spacecraft.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 17-25
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    Drops and Bubble in Materials Science (1982)
    In:  CASI
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    Description: The formation of extended p-n junctions in semiconductors by drop migration, mechanisms and morphologies of migrating drops and bubbles in solids and nucleation and corrections to the Volmer-Weber equations are discussed. Bubble shrinkage in the processing of glass, the formation of glass microshells as laser-fusion targets, and radiation-induced voids in nuclear reactors were examined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 1-6
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    Normal modes of a compound drop (1982)
    In:  CASI
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    Description: The modes are characterized by their frequency, the attendant displacement of fluid boundaries, and the flow pressure fields within the fluids. The drops consist of three fluids; a core fluid, a fluid shell surrounding the core, and a host fluid surrounding the shell. These fluids are assumed to be inviscid and incompressible, and the core and the shell to be concentric. The theory is obtained by linearization of the equations of fluid motion to the lowest order of nonlinearity that yields the normal modes. Numerical values of mode frequencies and the associated relative displacements of the fluid boundaries are presented for several specific systems, and the results compared with observations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 7-14
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    The size and shape of equilibrium capillary surfaces (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The classical theory of capillary is concerned largely with size and shape estimates in symmetric asymptotic configurations. Recent developments leading to global results for all symmetric cases, and to qualitative information on asymptotic properties are discussed. Additional stability criteria are described. Asymmetric situations leading to behavior that differs strikingly from the symmetric case are discussed. When gravity vanishes, capillary surfaces in the accustomed sense may not appear. The question of characterizing those tubes in which surfaces can be found has partially been settled. Progress toward determining the effects of contact angle hysteresis in cases of particular interest is reported.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 280-285
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    Solidification of carbon-oxygen white dwarfs (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The internal structure of white dwarfs is discussed. Highly correlated plasmas are reviewed. Implications for phase separation in the core of cooling white dwarfs are considered. The consequences for evolution of white dwarfs are addressed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 222-226
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    The mechanical design of a vapor compressor for a heat pump to be used in space (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A heat pump developed for use in Spacelab as a stand-alone refrigeration unit as well as within a fluid loop system is discussed. It will provide an active thermal control for payloads. Specifications for the heat pump were established: (1) heat removal rates at the source; (2) heat source temperatures from room temperature; (3) heat-sink fluid temperatures at condenser inlet; and (4) minimum power consumption. A reversed Carnot cycle heat pump using Freon 12 as working fluid incorporating a one-cylinder reciprocating compressor was selected. The maximum crankshaft speed was fixed relatively high at 100 rpm. The specified cooling rates then made it necessary to select a cylinder volume of 10 cu cm, which was obtained with a bore of 40 mm and a stroke of 8 mm.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Kennedy Space Center The 16th Aerospace Mech. Symp.; p 329-340
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    Historical perspectives on thermostructural research at the NACA Langley Aeronautical Laboratory from 1948 to 1958 (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Some of the early research on structural problems produced by aerodynamic heating, conducted at the Langley Aeronautical Laboratory of the National Advisory Committee for Aeronautics from 1948 to 1958 is described. That was the last decade of the NACA; in 1958 NACA became the nucleus of NASA. The NACA initially contracted for research but was aware that a well-equipped and suitably staffed laboratory was required to fulfill its obligations. Langley was established in 1920; the other listed were added during the NACA expansion in the World War II years. Some specific research activities are described, starting with calculation of the temperature of the structure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 363-392
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    Evaluation of an improved finite-element thermal stress calculation technique (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A procedure for generating accurate thermal stresses with coarse finite element grids (Ojalvo's method) is described. The procedure is based on the observation that for linear thermoelastic problems, the thermal stresses may be envisioned as being composed of two contributions; the first due to the strains in the structure which depend on the integral of the temperature distribution over the finite element and the second due to the local variation of the temperature in the element. The first contribution can be accurately predicted with a coarse finite-element mesh. The resulting strain distribution can then be combined via the constitutive relations with detailed temperatures from a separate thermal analysis. The result is accurate thermal stresses from coarse finite element structural models even where the temperature distributions have sharp variations. The range of applicability of the method for various classes of thermostructural problems such as in-plane or bending type problems and the effect of the nature of the temperature distribution and edge constraints are addressed. Ojalvo's method is used in conjunction with the SPAR finite element program. Results are obtained for rods, membranes, a box beam and a stiffened panel.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 115-131
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    Interactive modeling, design and analysis of large spacecraft (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An efficient computer aided design and analysis capability applicable to large space structures was developed to relieve the engineer of much of the effort required in the past. The automated capabilities can be used to rapidly synthesize, evaluate, and determine performance characteristics and costs for future large spacecraft concepts. The interactive design and evaluation of advanced spacecraft program (IDEAS) is used to illustrate the power, efficiency, and versatility of the approach. The coupling of space environment modeling algorithms with simplified analysis and design modules in the IDEAS program permits rapid evaluation of completing spacecraft and mission designs. The approach is particularly useful in the conceptual design phase of advanced space missions when a multiplicity of concepts must be considered before a limited set can be selected or more detailed analysis. Integrated spacecraft systems level data and data files are generated or subsystems and mission reexamination and/or refinement and for more rigorous analyses.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 199-219
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    Development of a reduced basis technique for transient thermal analysis (1982)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A technique to reduce the degrees of freedom in static and dynamic problems, the reduced basis method, is described. The method combines the classical Rayleigh-Ritz approximation with contemporary finite element methods to retain modeling versatility as the degrees of freedom are reduced. Applications to a nonlinear dynamic response problem are discussed efforts to apply the method to nonlinear transient thermal response problems are summarized. The selection of basis vectors for reducing the system of equations is addressed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Computational Aspects of Heat Transfer in Struct.; p 133-146
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    Applications of perturbation techniques (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Two perturbation techniques were applied to two singular perturbation problems in heat transfer to obtain uniformly valid solutions which can serve as benchmarks for finite difference and finite element techniques. In the first problem, the method of strained parameters coupled with the application of a solvability condition is used to obtain a uniform solution for the problem of unsteady heat conduction in a long nearly circular cylinder. In the second problem, the method of matched asymptotic expansion coupled with Van Dyke's matching principle is used to obtain a uniform solution for the problem of one dimensional conduction-convection heat transfer of a uniform fluid flow.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 147-160
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  • 85
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    Thermal capabilities and graphical output of PAFEC (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The program for automatic finite element calculations (PAFEC) developed for the computation of heat transfer in structures is discussed. The passive and interactive graphics capabilities of the PAFEC system are presented and future developments are outlined. This finite element system is shown to have significant thermal capabilities in support of its general structures. The program offers the following types of analysis: interactive graphics; user defined program control steps; steady state, transient heat transfer; boundary element methods; linear static, stress and displacements; modes and frequencies calculations; direct dynamic time intergration; frequency response analysis; elastohydrodynamic lubrication; large deflection analysis, buckling; creep and plasticity analysis; and substructures analysis.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Langley Research Center Computational Aspects of Heat Transfer in Struct.; p 21-33
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  • 86
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    Bubble in a corner flow (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The distortion of a two-dimensional bubble (or drop) in a corner of angle delta, due to the flow of an inviscid incompressible fluid around it, is examined theoretically. The flow and the bubble shape are determined as functions of the angle delta, the contact angle beta and the cavitation number gamma. The problem is formulated as an integrodifferential equation for the bubble surface. This equation generalized the integrodifferential equations derived by Vanden-Broeck and Keller. The shape of the bubble is found approximately by using the slender body theory for bubbles. When gamma reaches a critical value gamma sub 0 (beta, delta), opposite sides of the bubble touch each other. Two different families of solution for gamma gamma sub 0 are obtained. In the first family opposite sides touch at one point. In the second family contact is allowed along a segment.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 336-343
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  • 87
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    The motion of a drop in a rigid surface (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The assumptions of a region of slip near a moving contact line (to remove the force singularity) and a constant contact angle are used to obtain the equation for the shape of a thin drop of liquid resting on a rigid plane. Three asymptotic expansions are matched together to obtain an expression for the rate at which the drop spreads. Some cases of sliding motion are also examined. Although the technique is presented here for thin drops only, it can also be applied to drops of arbitrary size.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 315-321
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  • 88
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    Numerical methods and calculations for droplet flow, heating and ignition (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A numerical method was devised and employed to solve a variety of problems related to liquid droplet combustion. The basic transport equations of mass, momentum and energy were formulated in terms of generalized nonorthogonal coordinates, which allows for adaptive griding and arbitrary particle shape. Example problems are solved for internal droplet heating, droplet ignition and high Reynolds number flow over a droplet.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 358-365
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  • 89
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    Capillary forces exerted by liquid drops caught between crossed cylinders. A 3-D meniscus problem with free contact line (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The Young-Laplace equation is solved for three-dimensional menisci between crossed cylinders, with either the contact line fixed or the contact angle prescribed, by means of the Galerkin/finite element method. Shapes are computed, and with them the practically important quantities: drop volume, wetted area, capillary pressure force, surface tension force, and the total force exerted by the drop on each cylinder. The results show that total capillary force between cylinders increases with decreasing contact angle, i.e. with better wetting. Capillary force is also increases with decreasing drop volume, approaching an asymptotic limit. However, the wetted area on each cylinder decreases with decreasing drop volume, which raises the question of the optimum drop volume to strive for, when permanent bonding is sought from solidified liquid. For then the strength of the bond is likely to depend upon the area of contact, which is the wetted area when the bonding agent was introduced in liquid form.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 308-314
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  • 90
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    Drop processes in natural clouds (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A model of the diffusive mixing of dry and cloudy air, a process considered to be fundamental to the development of natural clouds, is presented. Water drops are formed at the cloud base by condensation upon nuclei and as they rise they grow by vapor diffusion in the slightly supersaturated environment of the clouds. Turbulent mixing between cloudy air and undersaturated air entrained from outside produces fluctuations in supersaturation, not linked to changes in vertical velocity, which cause broadening of the condensate spectrum and the rapid production of droplets large enough to engage in growth by coalescence. The probabilities of permanent union or the production of satellite droplets following the collision of a pair of raindrops is a sensitive function of several parameters. In some circumstances electrohydrodynamic bursting may influence the properties of clouds.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 227-238
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  • 91
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    Fragmentation of interstellar clouds and star formation (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The principal issues are addressed: the fragmentation of molecular clouds into units of stellar mass and the impact of star formation on molecular clouds. The observational evidence for fragmentation is summarized, and the gravitational instability described of a uniform spherical cloud collapsing from rest. The implications are considered of a finite pressure for the minimum fragment mass that is attainable in opacity-limited fragmentation. The role of magnetic fields is discussed in resolving the angular momentum problem and in making the collapse anisotropic, with notable consequences for fragmentation theory. Interactions between fragments are described, with emphasis on the effect of protostellar winds on the ambient cloud matter and on inhibiting further star formation. Such interactions are likely to have profound consequences for regulating the rate of star formation and on the energetics and dynamics of molecular clouds.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 214-221
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  • 92
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    Collapse of large vapor bubbles (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The refilling of propellant tanks while in a low-gravity environment requires that entrapped vapor bubbles be collapsed by increasing the system pressure. Tests were performed to verify the mechanism of collapse for these large vapor bubbles with the thermodynamic conditions, geometry, and boundary conditions being those applicable to propellant storage systems. For these conditions it was found that conduction heat transfer determined the collapse rate, with the specific bubble geometry having a significant influence.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 187-194
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  • 93
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    Size distribution of oceanic air bubbles entrained in sea-water by wave-breaking (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The size of oceanic air bubbles produced by whitecaps and wave-breaking is determined. The production of liquid aerosols at the sea surface is predicted. These liquid aerosols are at the origin of most of the particulate materials exchanged between the ocean and the atmosphere. A prototype was designed and built using an optical technique based on the principle of light scattering at an angle of ninety degrees from the incident light beam. The output voltage is a direct function of the bubble diameter. Calibration of the probe was carried out within a range of 300 microns to 1.2 mm. Bubbles produced by wave-breaking in a large air-sea interaction simulating facility. Experimental results are given in the form of size spectrum.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 182-186
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  • 94
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    Large amplitude drop shape oscillations (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An experimental study of large amplitude drop shape oscillation was conducted in immiscible liquids systems and with levitated free liquid drops in air. In liquid-liquid systems the results indicate the existence of familiar characteristics of nonlinear phenomena. The resonance frequency of the fundamental quadrupole mode of stationary, low viscosity Silicone oil drops acoustically levitated in water falls to noticeably low values as the amplitude of oscillation is increased. A typical, experimentally determined relative frequency decrease of a 0.5 cubic centimeters drop would be about 10% when the maximum deformed shape is characterized by a major to minor axial ratio of 1.9. On the other hand, no change in the fundamental mode frequency could be detected for 1 mm drops levitated in air. The experimental data for the decay constant of the quadrupole mode of drops immersed in a liquid host indicate a slight increase for larger oscillation amplitudes. A qualitative investigation of the internal fluid flows for such drops revealed the existence of steady internal circulation within drops oscillating in the fundamental and higher modes. The flow field configuration in the outer host liquid is also significantly altered when the drop oscillation amplitude becomes large.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 143-150
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  • 95
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    Liquid drop technique for generation of organic glass and metal shells (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: It was found that liquid drop techniques are very useful in several diverse areas. For producing very uniform metallic, organic, inorganic and, on particular, glassy shells, the liquid jet method is the most reproducible and exceptionally useful of all the techniques studied. The technique of capillary wave synchronization of the break-up of single and multiple component jets was utilized to produce uniform sized liquid drops and solid particles, and hollow liquid and solid shells. The technique was also used to encapsulate a number of liquids in impermeable spherical shells. Highly uniform glass shells were made by generating uniform drops of glass forming materials in an aqueous solution, subsequently evaporating the water, and then fusing and blowing the remaining solids in a high temperature vertical tube furnace. Experimental results are presented and the critical problems in further research in this field are discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 124-128
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  • 96
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    Generation of a strong core centering force in a submillimeter compound droplet system (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: By amplitude-modulating the driving voltage of an acoustic levitating apparatus, a strong core centering force was generated in a submillimeter compound droplet system suspended by the radiation pressure in a gaseous medium. Depending on the acoustic characteristics of the droplet system, it was found that the technique can be utilized advantageously in the multiple-layer coating of an inertial confinement fusion pellet.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 107-111
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  • 97
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    Hydrodynamic performance of an annular liquid jet: Production of spherical shells (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An annular jet flow of liquid surrounding a flow of gas at its core is extremely unstable. Axisymmetric oscillations arise spontaneously, and grow with such rapidity along the axial dimension that a pinch-off of the liquid and an encapsulation of the core gas occurs within as few as four jet diameters. The shells which result thereby may be described as thick-wall bubbles, for which van der Waals forces are unimportant. A description is given of the fluid dynamic processes by which the shells are formed, and of means for preserving and promoting the geometrical of the product. The forming of metallic shells is mentioned.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 79-87
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  • 98
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    Mechanisms of droplet combustion (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The fundamental physico-chemical mechanisms governing droplet vaporization and combustion are discussed. Specific topics include governing equations and simplifications, the classical d(2)-Law solution and its subsequent modification, finite-rate kinetics and the flame structure, droplet dynamics, near- and super-critical combustion, combustion of multicomponent fuel blends/emulsions/suspensions, and droplet interaction. Potential research topics are suggested.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 39-53
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  • 99
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    Acoustically induced oscillation and rotation of a large drop in space (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A 2.5 cm diameter water drop was successfully deployed and manipulated in a triaxial acoustic resonance chamber during a 240 sec low-gravity SPAR rocket flight. Oscillation and rotation were induced by modulating and phase shifting the signals to the speakers. Portions of the film record were digitized and analyzed. Spectral analysis brought out the n = 2, 3, 4 free oscillation modes of the drop, its very low-frequency center-of-mass motion in the acoustic potential well, and the forced oscillation frequency. The drop boundaries were least-square fitted to general ellipses, providing eccentricities of the distorted drop. The normalized equatorial area of the rotating drop was plotted vs a rotational parameter, and was in excellent agreement with values derived from the theory of equilibrium shapes of rotating liquid drops.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 31-38
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  • 100
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    The production of drops by the bursting of a bubble at an air liquid interface (1982)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The fundamental mechanism arising during the bursting of a bubble at an air-liquid interface is described. A single bubble was followed from an arbitrary depth in the liquid, up to the creation and motion of the film and jet drops. Several phenomena were involved and their relative order of magnitude was compared in order to point out the dimensionless parameters which govern each step of the motion. High-speed cinematography is employed. The characteristic bubble radius which separates the creation of jet drops from cap bursting without jet drops is expressed mathematically. The corresponding numerical value for water is 3 mm and agrees with experimental observations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JPL Proc. of the 2d Intern. Colloq. on Drops and Bubbles; p 157-165
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