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  • FLUID MECHANICS AND HEAT TRANSFER  (595)
  • 1990-1994
  • 1980-1984  (595)
  • 1970-1974
  • 1982  (362)
  • 1980  (233)
  • 1929
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  • 1990-1994
  • 1980-1984  (595)
  • 1970-1974
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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    Transient thermocapillary flow in thin liquid layers (1980)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 24 p
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  • 4
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    Surface-tension gradient induced flows at reduced gravity, introduction (1980)
    In:  Other Sources
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    Publication Date: 2011-08-19
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 21 p
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  • 5
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    A numerical study of the effects of heat diffusion through the base of the mixed layer (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: In the present paper, a simple numerical model is used to study the warming of the mixed layer during the early summer. It is shown that the springtime temperature increase in the layer below the mixed layer (for example, in the cold pool on a continental shelf) has a maximum value which occurs for a limiting value of the surface heat flux. This is a result of the positive feedback at large Richardson numbers between stability and vertical diffusion of heat. The springtime temperature increase in the mixed layer increases nonlinearly with surface heat flux, because of the same positive feedback. The effects of interseasonal fluctuations of the surface heat flux on the spring and summer mixed layer and deeper temperature increases can be as great as the effect of interseasonal fluctuations of the average heat flux.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Geophysical Research; 85; Sept. 20
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  • 6
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    New class of asymmetric shapes of rotating liquid drops (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: Shapes and stability of surface-tension-endowed drops rotating rigidly at fixed angular momentum are calculated by finite-element analysis. A new family of asymmetric two-lobed drop shapes is discovered that branches from, and rejoins, the Pik-Pichak family of symmetric two-lobed shapes. The computations are verified for axisymmetric and symmetric two-lobed drop shape by comparison with previous approximations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physical Review Letters; 45; July 21
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  • 7
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    Normal and abnormal turbulent transport in a stratified medium (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: The influences of memory effects, coupling between velocity and temperature fluctuations and tensorial transport properties on momentum and heat transfers in turbulent flow which do not follow the Boussinesq relation are examined. It is shown that the memory effect, represented by the Lagrangian of the velocity gradients, can account for the decoupling between the flux and the gradient, while the tensorial properties of the transport coefficients allow a normal Boussinesq-type transfer with memory and anomalous counter-gradient or gradient-less transport.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 8
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    Effect of temperature on surface noise (1980)
    In:  Other Sources
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    Publication Date: 2011-08-17
    Description: An experimental work is discussed whose objective was to obtain data that show the effect of temperature and temperature fluctuations on surface noise. This was accomplished experimentally by immersing a small chord airfoil in the turbulent airstream of a hot jet. The theory and experiment reported by Olsen (1976) provided a guide for designing and validating the hot jet experiment and for interpreting the data. It is shown that increased temperature causes a small decrease in the sound levels; at the same time it causes a shift in the spectra that is smaller but similar to the shift observed with subsonic hot jet noise.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA Journal; 18; Mar. 198
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  • 9
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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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  • 10
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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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  • 11
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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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  • 12
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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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  • 13
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    Gas diffusion in multibubble systems (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: A model is proposed for the study of the growth and shrinkage of gas bubbles in systems containing many gas bubbles. The key feature of this model is the replacement of the bubbles by point sources of gas concentration. Calculations are performed in the simple case of an initial uniform array of bubbles of equal radii.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Chemical Engineering Science; 35; 1980
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  • 14
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    Vortex methods for flow simulation (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: Recent progress in the development of vortex methods and their applications to the numerical simulation of incompressible fluid flows are reviewed. Emphasis is on recent results concerning the accuracy of these methods, improvements in computational efficiency, and the development of three-dimensional methods. Simulations of several example flows which display some of the strengths and weaknesses of vortex methods are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 37; Oct. 198
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  • 15
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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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  • 16
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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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  • 17
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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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  • 18
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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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  • 19
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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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  • 20
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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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  • 21
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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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  • 22
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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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  • 23
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    Vortex methods for two- and three-dimensional flow simulations (1980)
    In:  Other Sources
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    Publication Date: 2011-08-18
    Description: The point vortex and vortex blob methods for two dimensional flows are presented. Several results are discussed concerning the numerical analysis of the latter scheme, e.g., the preservation of globally conserved quantities and the analysis of the spatial discretization error resulting from the convection of fixed blobs of vorticity. An application to the two dimensional mixing layer is briefly described. The contour dynamics method is also discussed. The simulation of three dimensional flows with vortex methods is discussed. A natural way to represent the vorticity is in the form of closed tubes of filaments of vorticity, although other schemes are examined. Applications to aircraft trailing vortices and to a turbulent spot in a laminar boundary layer are presented. Hybrid schemes that use an Eulerian mesh to solve the Poisson equation for the velocity field are discussed. The goal of these schemes is to avoid the high cost of the Biot-Savart integration if many vortex elements are used while enjoying most of the advantages of pure Lagrangian schemes.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Von Karman Inst. for Fluid Dyn. Computational Fluid Dyn., Vol. 2; 52 p
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  • 24
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    Exchange of stability for a column of fluid with variable Rayleigh number under free boundary conditions (1980)
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    Publication Date: 2011-08-18
    Description: The exchange of stabilities is demonstrated for a system with harmonic boundary conditions. The motion of fluid in the presence of temperatures gradients is described. It is shown that this principle holds under free, but not rigid or semirigid, boundary conditions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 25
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    Measurement of velocity fields in fluid dynamics experiments (1980)
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    Publication Date: 2011-08-18
    Description: A microcomputer-video system was used to measure both spatial and temporal variations of two dimensional fluid flow velocity fields. The system utilizes two methods: the first method is the traditional one in which tracers are introduced into the fluid and their position compared at two closely spaced times; and the second method involves scattering coherent light in the fluid and obtaining motion by analyzing the multiple exposed speckle pattern recorded on photographic film.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 6 p
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  • 26
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    Stability of the stratifield cylindrical annulus flow (1980)
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    Publication Date: 2011-08-18
    Description: The linear stability analysis for the stratified flow between two rotating circular cylinders is formulated. Two approaches for the stability analysis are presented. The first approach results in an algebraic eigenvalue problem, while the second results in an initial value problem for the perturbation function. The advantages and disadvantages of both approaches are discussed and a preferable numerical solution technique is outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 13 p
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  • 27
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    Axially symmetric motion of a rotating stratified fluid (1980)
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    Publication Date: 2011-08-18
    Description: The spherical modeling of geophysical fluid flow is examined. In particular the extension of some previous work done in spherical geometry to the specific case of interest in the Spacelab atmospheric circulation experiment is discussed. This involves changing the boundary conditions under which the basic equations are to be solved. For simplicity the linear, axially symmetric steady state solution is sought.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Alabama Univ. Res. Rept.: The 1980 NASA(ASEE Summer Fac. Fellowship Program; 17 p
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  • 28
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    Experimental investigation of a three dimensional turbulent boundary layer with a non disappearing pressure gradient (1980)
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    Publication Date: 2011-08-17
    Description: The results of measuring profiles of temporally determined velocities and Reynolds tension, wall shear stresses and pressure distribution in a three dimensional, turbulent boundary layer with pressure gradients in both tangential directions are reported. For determining the velocities X wire probes were used whose cooling was gauged according to magnitude and direction of the flow and was described with an effective cooling speed. In the evaluation consideration is given to the directional sensitivity of the hot wire. The ratio of the turbulence viscosities is calculated for both tangential directions and is found to be approximately N equals 1.2. Further, the profiles of the mixing path lengths for the flow direction are found to vary only slightly with increasing X-coordinates, while the boundary layer thickness increases substantially. The relationships of turbulent shear stress to turbulent, kinetic fluctuation energy is approximately constant over a large part of the boundary layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 29
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    The shape and stability of rotating liquid drops (1980)
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    Publication Date: 2011-08-17
    Description: Equilibrium shapes and stability of rotating drops held together by surface tension are found by computer-aided analysis that uses expansions in finite-element basis functions. Shapes are calculated as extrema of appropriate energies. Stability and relative stability are determined from curvatures of the energy surface in the neighborhood of the extremum. Families of axisymmetric, two-, three-, and four-lobed drop shapes are traced systematically. Bifurcation and turning points are located and the principle of exchange of stabilities is tested. The axisymmetric shapes are stable at low rotation rates but lose stability at the bifurcation to two-lobed shapes. Two-lobed drops isolated with constant angular momentum are stable. The results bear on experiments designed to further those of Plateau (1863).
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
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  • 30
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    Examination of group-velocity criterion for breakdown of vortex flow in a divergent duct (1980)
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    Publication Date: 2011-08-17
    Description: A group-velocity criterion for vortex breakdown implied by wave trapping theory is applied to vortex flows in a slightly divergent duct that exhibits breakdown. The group velocities for both symmetric (n = 0) and nonsymmetric (n = plus or - 1) modes of wave propagation are calculated for the experimental data. It is found that the flow ahead of the breakdown region is always supercritical and stable to these modes of disturbances. However, the flow field behind the breakdown region may be either supercritical or subcritical to the modes n = 0 and n = 1, and always supercritical to mode n = -1. The flow field behind this breakdown region is unstable to the asymmetric mode disturbance (n = 1) for a finite range of wavenumbers. The calculated frequencies of the unstable disturbances are in good agreement with the frequencies obtained from the experimental measurements.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Physics of Fluids; 23; May 1980
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  • 31
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    On the numerical solution of time-dependent viscous incompressible fluid flows involving solid boundaries (1980)
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    Publication Date: 2011-08-17
    Description: An inherent numerical problem associated with the fully explicit pseudospectral numerical simulation of the incompressible Navier-Stokes equation for viscous flows with no-slip walls is described. A semi-implicit scheme which circumvents this numerical difficulty is presented. In this algorithm the equation of continuity rather than the Poisson equation for pressure is solved directly. Pseudospectral formulation of the channel flow problem using Fourier series and Chebyshev polynomials expansions is given for this scheme. An example demonstrating the applicability of the method is given.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics; 35; May 1980
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  • 32
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    Simulation of flat-plate turbulent boundary layers in cryogenic tunnels (1980)
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    Publication Date: 2011-08-17
    Description: The magnitudes of real-gas effects on flat-plate turbulent boundary layer simulations in a cryogenic nitrogen wind tunnel are investigated in order to determine the validity of the method used by Inger (1979) to estimate real-gas effects. Boundary layer solutions for real gases, ideal gases with a specific heat ratio of 1.6 and ideal diatomic gases (specific heat ratio 1.4) were obtained for the worst case conditions of maximum stagnation pressure (9 atm), minimum stagnation temperature (120 K) and Mach number of 1.2. Calculated boundary layer parameters such as friction coefficient and displacement thickness are shown to agree closely for the real gas and the ideal diatomic gas (specific heat ratio 1.4), while the ideal gas solution used by Inger is shown to differ from the real-gas values considerably. Results indicate that real-gas effects on a flat-plate turbulent boundary layer simulation in a cryogenic nitrogen tunnel are insignificant, and suggest the unlikelihood of the large real-gas effects reported by Inger for turbulent boundary layer shock interactions.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Aircraft; 17; Apr. 198
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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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    On current aspects of finite element computational fluid mechanics for turbulent flows (1982)
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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.
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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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    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.
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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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    Topology of three-dimensional separated flows (1982)
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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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    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.
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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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    ADI on staggered mesh - A method for the calculation of compressible convection (1982)
    In:  Other Sources
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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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  • 42
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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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    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.
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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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    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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    Pointwise and scanning laser anemometer measurements in steady and unsteady separated turbulent boundary layers (1982)
    In:  Other Sources
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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.
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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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    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
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    Large eddy simulation of turbulent channel flow: ILLIAC 5 calculation (1980)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: The capabilities of large eddy simulation in the prediction and analyses of wall-bounded turbulent shear flows are demonstrated. The dynamical equations for large scale field motions are derived. The computational grid network is described and its relation to the observed physical length scales in the flow are discussed. Some aspects of the mechanics and structure of the flow are examined both in the vicinity of the wall and in regions away from the wall. An attempt is made to correlate numerical results with laboratory observations. Other significant observations and conclusions are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Turbulent Boundary Layers; 18 p
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    Developments in the computation of turbulent boundary layers (1980)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: Two methods of turbulence computation are discussed in terms of their basic simularities. It is shown that the two methods are interrelated and that each can gain from advances in the other. The degree of success of a pair of increasingly complex Reynolds stress models to broaden their range of applicability is examined through comparison with experimental data for a variety of flow conditions. An example of a large eddy simulation is presented, compared with experimental results, and used to evaluate the models for pressure rate of strain correlation and dissipation in the Reynolds averaged equations.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Turbulent Boundary Layers; 23 p
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    A Navier-Stokes fast solver for turbulence modeling applications (1980)
    In:  CASI
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    Publication Date: 2017-10-02
    Description: A computer code for the evaluation and/or optimization of the predicative potential of second order turbulent closure models in simple two dimensional flow configurations is discussed. A procedure for the numerical solution of the steady constant property Navier-Stokes equations are described together with algebraic, one dimensional and two dimensional equations of turbulence closure models. Four turbulence models are compared with several sets of experimental data. The effects of initial conditions and boundary conditions are also described. The effects of purely numerical parameters, such as mesh size, boundary locations, and convergence criteria are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AGARD Turbulence Boundary Layers; 16 p
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    Motion induced by capillarity (1980)
    In:  Other Sources
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    Publication Date: 2016-03-09
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Surface-Tension Gradient Induced Flows at Reduced Gravity; 19 p
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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
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    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
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    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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    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
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    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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    NASTRAN thermal analyzer in a unified finite-element treatment of thermo-structural analyses (1982)
    In:  CASI
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    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
    Details
    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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    Thermal protection of reentry vehicles by actively cooled nosetips (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Analytical modeling efforts and clear-air ground test results of a transportation-cooled nosetips (TCNT) design are presented. The discrete water injection platelet TCNT described was conceived and created to achieve the performance requirements for severe reentry vehicle trajectories. Thermal performance computer modeling techniques, combing both local heat blockage and boundary layer recovery enthalpy reduction are outlined.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Johnson Space Center The 11th Space Simulation Conf.; p 331-346
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  • 70
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    An experimental investigation of circulation control flow fields using holographic interferometry (1982)
    In:  CASI
    Details
    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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  • 71
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    Airborne measurement of atmospheric turbulence (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A system capable of making measurements of fluctuating atmospheric density is described. Spatial scales required in assessing the quality of coherent radiation propagation are discussed. The special sensors, aircraft installation, data reduction procedures, and other special requirements necessary to obtain meaningful atmospheric turbulence data are also described. The spectral distribution of density fluctuation are presented.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 493-514
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  • 72
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    Lear jet boundary layer/shear layer laser propagation experiments (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Optical degradations of aircraft turbulent boundary layers with shear layers generated by aerodynamic fences are analyzed. A collimated 2.5 cm diameter helium-neon laser (0.63 microns) traversed the approximate 5 cm thick natural aircraft boundary layer in double pass via a reflective airfoil. In addition, several flights examined shear layer-induced optical degradation. Flight altitudes ranged from 1.5 to 12 km, while Mach numbers were varied from 0.3 to 0.8. Average line spread function (LSF) and Modulation Transfer Function (MTF) data were obtained by averaging a large number of tilt-removed curves. Fourier transforming the resulting average MTF yields an LSF, thus affording a direct comparison of the two optical measurements. Agreement was good for the aerodynamic fence arrangement, but only fair in the case of a turbulent boundary layer. Values of phase variance inferred from the LSF instrument for a single pass through the random flow and corrected for a large aperture ranged from 0.08 to 0.11 waves (lambda = .63 microns) for the boundary layer. Corresponding values for the fence vary from 0.08 to 0.16 waves. Extrapolation of these values to 10.6 microns suggests negligible degradation for a CO2 laser transmitted through a 5 cm thick, subsonic turbulent boundary layer.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 397-414
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    Overview of recent aero-optics flight tests (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A chronological overview of aero-optics test flights is presented highlighting the objectives and conclusions from the tests. Flight tests performed in coordination with the PRESS reentry observation missions and the ALL Cycle 2 laser propagation and tracking demonstrations are described addressing the identification and quantification of distortion phenomena. Finally, current aero-optics flight investigations of an atmospheric turbulence probe are briefly discussed.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 363-395
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    Optical phase distortion due to compressible flow over laser turrets (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Analytical models for optical phase distortion due to compressible flow over a laser turret are developed. Phase distortion is calculated for both blunt and small perturbation turrets. For the blunt turret, the Janzen-Rayleigh technique is used to determine the flow field. Phase distortions of 2.2 wavelengths at 3.8 microns are calculated for the blunt turret. For small perturbation turrets, a versatile analytical model is developed for a turret on a fuselage with circular cross section. With a two dimensional Fourier series representation of the turret, any shape can be considered. Both subsonic and supersonic flows can be calculated. Phase distortions of 1.2 wavelengths at 3.8 microns are calculated for one turret at high subsonic Mach number. In addition to being of value for laser turrets, the methods are applicable to reconnaissance aircraft using photographic equipment and cruise missiles using celestial navigation.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 287-325
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    Inviscid Flow Field Effects: Experimental results (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The aero-optical distortions due to invisid flow effects over airborne laser turrets is investigated. Optical path differences across laser turret apertures are estimated from two data sources. The first is a theoretical study of main flow effects for a spherical turret assembly for a Mach number (M) of 0.6. The second source is an actual wind tunnel density field measurement on a 0.3 scale laser turret/fairing assembly, with M = 0.75. A range of azimuthal angles from 0 to 90 deg was considered, while the elevation angle was always 0 deg (i.e., in the plane of the flow). The calculated optical path differences for these two markedly different geometries are of the same order. Scaling of results to sea level conditions and an aperture diameter of 50 cm indicated up to 0.0007 cm of phase variation across the aperture for certain forward look angles and a focal length of F = -11.1 km. These values are second order for a 10.6 micron system.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation Aircraft (SEE N80-25588 16-34)
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    Prediction of optical propagation losses through turbulent boundary/shear layers (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A simplified mathematical model was developed which predicts the optical propagation losses which occur when an optical beam of given wave length passes through a turbulent boundary layer or shear layer. The optical losses are predicted in terms of line spread function (or Strehl ratio) and modulation transfer function by using experimentally determined values of layer thickness, streamwise, lateral and beamwise density fluctuation length scales, and distribution of the standard deviation of the density fluctuations through the turbulent layer. The prediction model was applied to the analysis of a number of selected cases of interest from the aerodynamic-optical interaction wind-tunnel investigation conducted in the NASA-Ames 1.83 x 1.83 meter (6 x 6 ft) wind tunnel. Direct optical measurements are compared with the results predicted by the aerodynamic analysis.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 183-229
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  • 77
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    Flow visualization techniques in the Airborne Laser Laboratory program (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: A turret/fairing assembly for laser applications was designed and tested. Wind tunnel testing was conducted using flow visualization techniques. The techniques used have included the methods of tufting, encapsulated liquid crystals, oil flow, sublimation and schlieren and shadowgraph photography. The results were directly applied to the design of fairing shapes for minimum drag and reduced turret buffet. In addition, the results are of primary importance to the study of light propagation paths in the near flow field of the turret cavity. Results indicate that the flow in the vicinity of the turret is an important factor for consideration in the design of suitable turret/fairing or aero-optic assemblies.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 537-565
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  • 78
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    Cycle II.5 aircraft aero-optical turbulent boundary-layer/shear-layer measurements (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: The aero-optical effects associated with propagating a laser beam through aircraft turbulent boundary layers and shear layers were examined. Observed laser optical performance levels were compared with those inferred from aerodynamic measurements of unsteady densities and correlation lengths within these random flows. Optical instrumentation included a fast shearing interferometer (FSI). A 9 cm diameter collimated helium neon laser beam made a double pass through the aircraft random flow via an airfoil mirror located one meter from the fuselage. Typical aircraft turbulent boundary layer thickness measured 0.3 meters. Averaging many FSI generated modulation transfer functions (MTFs) and Fourier transforming, this average yields the expected far field intensity degradation associated with an aircraft mounted laser system. Aerodynamic instrumentation included fine wire probes to measure unsteady temperature and mass flux. A laser doppler velocimeter measured unsteady velocity within the flows. An analysis of these data yielded point measurements of unsteady density and correlation length.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 465-491
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  • 79
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    Aero-optics overview (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Various aero-optical phenomena are discussed with reference to their effect on airborne high energy lasers. Major emphasis is placed on: compressibility effects induced in the surrounding flow field; viscous effects which manifests themselves as aircraft boundary layers or shear layers; inviscid flow fields surrounding the aircraft due to airflow around protuberance such as laser turret assemblies; and shocks, established whenever local flow exceeds Mach one. The significant physical parameters affecting the interaction of a laser beam with a turbulent boundary layer are also described.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 657-675
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  • 80
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    Summary of all cycle II.5 shear and boundary layer measurements, aerodynamics (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The two measurement systems were used to measure mean velocity and velocity, mass flux, and total temperature fluctuations in the turbulent boundary on the fuselage of a KC-135 aircraft. The boundary layer thickness ranged between about 20 and 30 cm for the range of flight Mach numbers from about 0.25 to 0.85 and Reynolds numbers between 3 and 6 x 10 to the 6th power/m. The adaptation of each system for use in airborne applications is discussed. The data obtained from each system are given and compared with each other and they indicate that the two systems represent viable ones for use in future airborne turbulence experiments.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 459-464
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    Unsteady density and velocity measurements in the 6 foot x 6 foot wind tunnel (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The methods used and the results obtained in four aero-optic tests are summarized. It is concluded that the rather large values of density fluctuation appear to be the result of much higher Mach number than freestream and the violent turbulence in the flow as it separates from the turret. A representative comparison of fairing on-fairing off rms density fluctuation indicates essentially no effect at M = 0.62 and a small effect at M = 0.95. These data indicate that some slight improvement in optical quality can be expected with the addition of a fairing, although at M = 0.62 its effect would be nil. Fairings are very useful in controlling pressure loads on turrets, but will not have first order effects on optical quality. Scale sizes increase dramatically with increasing azimuth angle for a reprensentative condition. Since both scale sizes and fluctuation levels increase (total turbulence path length also increases) with azimuth angle, substantial optical degradation might be expected. For shorter wave lengths, large degradations occur.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 153-181
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    Reduction of unsteady wind torques on an open port airborne optical turret (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Techniques for reducing the unsteady torques acting on the inner gimbal of a turret were developed. The reductions in the unsteady torques were obtained by using fixes that alter undesirable flow characteristics or change the acoustic properties of the turret cavity. These fixes were designed to be used in the subsonic and transonic flow regimes. The flow field about the turret generally three dimensional and turbulent, and shock waves formed because of the rapid acceleration of the compressible gas about the blunt turret. The situation was further complicated by the presence of the cavity flow, and the fact that the mouth of the cavity must sweep through a wide angular variation relative to the direction of the freestream. Results indicate that significant reductions of the unsteady pressures measured in the turret cavity could be obtained by the use of porous wind screens around the aperature of the cavity mouth.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 567-581
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    Aero-optical characterization of aircraft optical turrets by holography, interferometry and shadowgraph (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Density variations in the aircraft boundary layer, turret wakes and shock waves create distortion of an optical wavefront through associated refractive index variations. Such effects can be observed directly through optical flow visualization. The application of holographic interferometry, wave shearing interferometry, and laser shadowgraph to observe and quantify such effects is described. Examples of the results from five different wind tunnel tests are presented. The examples show that diagnostics have provided valuable qualitiative and quantitiative data. These include (1) wake dimensions, (2) optical strength of the flow field, (3) turbulence characterization, (4) shock location, and (5) direct observation of areo-optical effects.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 127-151
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  • 84
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    Turbulent two-dimensional jet flow and its effect on laser beam degradation (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: An experiment in which visible wavelength lasers traversed a well-documented two dimensional jet was conducted. Temperature perturbations varied from 0.25 to 1.80 K and velocity fluctuations ranged from 9.2 to 30.8 m/sec. Measured central spot intensities were as low as 18% of the undisturbed beam, depending on jet Mach number, beam position theory and experiment was two percent in terms of far field intensity. To supplement the flow field information, a laser Doppler velocimeter was developed to measure both mean and fluctuating velocities and a photo correlator was used as a signal processor.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 1-33
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  • 85
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    Overview of 6- X 6-foot wind tunnel aero-optics tests (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The splitter-plate arrangement used in tests in the 6 x 6 foot wind tunnel and how it was configured to study boundary layers, both heated and unheated, shear layers over a cavity, separated flows behind spoilers, accelerated flows around a turret, and a turret wake are described. The flows are characterized by examples of the steady-state pressure and of velocity profiles through the various types of flow layers.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 35-90
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  • 86
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    Measurement of external forces and torques on a large pointing system (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Methods of measuring external forces and torques are discussed, in general and as applied to the Large Pointing System wind tunnel tests. The LPS tests were in two phases. The first test was a preliminary test of three models representing coelostat, heliostat, and on-gimbal telescope configurations. The second test explored the coelostat configuration in more detail. The second test used a different setup for measuring external loads. Some results are given from both tests.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 583-613
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  • 87
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    Validity of small scale tests for turret/fairing loads and cavity effects (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: Data from several wind tunnel experiments along with available flight test data are used to discuss the validity of small scale tests and their inherent limitations. Tests were performed at transonic speeds to measure the turbulence levels in a cavity with and without a forward porous fence, turret drag with and without an aerodynamic fairing, and turret/fairing unsteady pressures.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 615-656
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  • 88
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    Summary of Aerodynamic Vibration Effects on ALL Turret (1980)
    In:  CASI
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    Publication Date: 2016-06-07
    Description: The effects of the airborne environment on a pointing and tracking system using a turret external to an aircraft are summarized. The data covered a series of flight tests and a span of seven years. The two major airborne effects were shown to be direct pressure loading of optical elements and vibrations of the entire turret. The direct optical loading problem was minimized by fence designs for the turret.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 515-535
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    Optical measurements of degradation in aircraft boundary layers (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: Visible wavelength measurements of the degradation of optical beams when transmitted through the thin aerodynamic boundary layers around an aircraft are reviewed. The measured results indicated degradation levels for the KC-135 airplanes between 0.10 to 0.13 lambda increasing to 0.18 lambda (rms wavefront distortion). For the Lear Jet, degradation with a 25 mm diameter optics was roughly 0.07 lambda. The corresponding infinite aperture degradation levels are also calculated. The corresponding measured correlation lengths of roughly 12 mm for the KC-135 aircraft and 6 mm for the Lear Jet scale to roughly 20 and 25 mm, respectively, for infinite apertures. These boundary layer correlation lengths do not appear to reflect the different boundary layer thicknesses on the two different aircraft.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: NASA. Ames Res. Center Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 415-457
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  • 90
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    Optimized laser turrets for minimum phase distortion (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: An analysis and computer program which optimizes laser turret geometry to obtain minimum phase distortion is described. Phase distortion due to compressible, inviscid flow over small perturbation laser turrets in subsonic or supersonic flow is calculated. The turret shape is determined by a two dimensional Fourier series; in a similar manner, the flow properties are given by a Fourier series. Phase distortion is calcualted for propagation at serveral combinations of elevation and azimuth angles. A sum is formed from the set of values, and this sum becomes the objective function for an optimization computer program. The shape of the turret is varied to provide minimum phase distortion.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Proc. of the Aero-Optics Symp. on Electromagnetic Wave Propagation from Aircraft; p 339-362
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  • 91
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    Thermal vacuum performance testing of the Space Shuttle Orbiter radiator system (1980)
    In:  CASI
    Details
    Publication Date: 2016-06-07
    Description: A space shuttle orbiter system thermal vacuum performance test was conducted at NASA-Johnson Space Center in Chamber A of the space environment simulation laboratory. The test of objective was to verify the radiator system heat rejection performance capability utilizing two development and two flight radiator panels comprising one of the two Orbiter Freon-21 coolant loops. Radiator performance over the range of expected flight conditions was as predicted, and there was no degradation of performance after extended vacuum exposure.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: The 11th Space simulation Conf.; p 305-317
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  • 92
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    Thermal radiation view factor: Methods, accuracy and computer-aided procedures (1982)
    In:  CASI
    Details
    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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  • 93
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    Some aspects of algorithm performance and modeling in transient thermal analysis of structures (1982)
    In:  CASI
    Details
    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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  • 94
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    A method to model latent heat for transient analysis using NASTRAN (1982)
    In:  CASI
    Details
    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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  • 95
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    Studies of the nucler equation of state using numerical calculations of nuclear drop collisions (1982)
    In:  CASI
    Details
    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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  • 96
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    Recent developments in thermal radiation system analyzer (Trasys) (1982)
    In:  CASI
    Details
    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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  • 97
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    Reentry heat transfer analysis of the space shuttle orbiter (1982)
    In:  CASI
    Details
    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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  • 98
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    The SPAR thermal analyzer: Present and future (1982)
    In:  CASI
    Details
    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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  • 99
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    The numerical analysis of the rotational theory for the formation of lunar globules (1982)
    In:  CASI
    Details
    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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  • 100
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    Fluid models and simulations of biological cell phenomena (1982)
    In:  CASI
    Details
    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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