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  • 1
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    A comparative study of advanced shock-capturing schemes applied to Burgers' equation (1992)
    In:  Other Sources
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    Publication Date: 2011-08-24
    Description: A systematic evaluation is conducted of all extant numerical schemes for nonlinear scalar transport problems, and several advanced shock-capturing schemes are used to solve the nonlinear Burgers' equation in order to characterize their ability to resolve the sharp discontinuity, expansion zone, and propagation and collision features of shocks. For discontinuous functions, the Warming-Beam scheme generates preshock wiggles, while the Lax-Wendroff scheme generates postshock ones. Such limiters as the MUSCL or the superbee are more compressive than minimod or monotonic limiters. The performance of such TVD schemes as the upwind, the symmetric, and the Roe-Sweby, resemble each other.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: Journal of Computational Physics (ISSN 0021-9991); 102; 1, Se; 139-159
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  • 2
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    Assessment of numerical methods for the solution of fluid dynamics equations for nonlinear resonance systems (1989)
    In:  Other Sources
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    Publication Date: 2013-08-29
    Description: The capability of accurate nonlinear flow analysis of resonance systems is essential in many problems, including combustion instability. Classical numerical schemes are either too diffusive or too dispersive especially for transient problems. In the last few years, significant progress has been made in the numerical methods for flows with shocks. The objective was to assess advanced shock capturing schemes on transient flows. Several numerical schemes were tested including TVD, MUSCL, ENO, FCT, and Riemann Solver Godunov type schemes. A systematic assessment was performed on scalar transport, Burgers' and gas dynamic problems. Several shock capturing schemes are compared on fast transient resonant pipe flow problems. A system of 1-D nonlinear hyperbolic gas dynamics equations is solved to predict propagation of finite amplitude waves, the wave steepening, formation, propagation, and reflection of shocks for several hundred wave cycles. It is shown that high accuracy schemes can be used for direct, exact nonlinear analysis of combustion instability problems, preserving high harmonic energy content for long periods of time.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: JHU, The 26th JANNAF Combustion Meeting, Volume 2; p 233-242
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  • 3
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    A study of pressure-based methodology for resonant flows in non-linear combustion instabilities (1992)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: This paper presents a systematic assessment of a large variety of spatial and temporal differencing schemes on nonstaggered grids by the pressure-based methods for the problems of fast transient flows. The observation from the present study is that for steady state flow problems, pressure-based methods can be very competitive with the density-based methods. For transient flow problems, pressure-based methods utilizing the same differencing scheme are less accurate, even though the wave speeds are correctly predicted.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 92-0779
    Format: text
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  • 4
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    Assessment of modern methods in numerical simulations of high speed flows (1992)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Results of extensive studies on CFD algorithms for 2D inviscid flows in Cartesian and body fitted coordinates geometries are reviewed. These studies represent part of an ongoing investigation of combustion instabilities involving the interactions of high-speed nonlinear acoustic waves. Four numerical methods for the treatment of high speed flows are compared, namely, Roe-Sweby TVD, Yee symmetric TVD; Osher-Chakravarthy TVD; and the Colella's multi-dimensional Godunov method.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 92-0052
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  • 5
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    A comparative study of advanced shock-capturing schemes applied to Burgers' equation (1990)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: Several variations of the TVD scheme, ENO scheme, FCT scheme, and geometrical schemes, such as MUSCL and PPM, are considered. A comparative study of these schemes as applied to the Burgers' equation is presented. The objective is to assess their performance for problems involving formation and propagation of shocks, shock collisions, and expansion of discontinuities.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-1445
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  • 6
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    Assessment of shock capturing schemes for resonant flows in nonlinear instability analysis (1990)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: The paper presents computational assessment of advanced numerical schemes for nonlinear acoustic problems related to combustion instabilities in liquid rocket engines. Several time-accurate, shock capturing schemes have been evaluated on a benchmark, closed-end resonant pipe flow problem. It involves the numerical solution of inviscid, compressible gas dynamics equations to predict acoustic wave propagation, wave steepening, formation of shocks, acoustic energy dissipation and wave-wall reflection for several hundred wave cycles. It was demonstrated that high accuracy TVD type schemes can be used for direct, exact nonlinear analysis of combustion instability problems, preserving high harmonic energy content for long periods of time. The selected scheme was then applied to analyze the acoustic responses of resonant pipe-resonator, radial acoustic modes and hub-baffle configurations. Interesting observations of wave shape and damping characteristics have been drawn from presented computational studies.
    Keywords: PROPELLANTS AND FUELS
    Type: AIAA PAPER 90-2358
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  • 7
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    Direct simulation for the instability and breakup of laminar liquid jets (1990)
    In:  Other Sources
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    Publication Date: 2019-06-28
    Description: A direct numerical simulation method is described for predicting the deformation of laminar liquid jets. In the present nonlinear direct simulation, the convective term, which has been discarded in past linear analyses by Rayleigh and others, is included in the hydrodynamic equations. It is shown that only by maintaining full complexity of the nonlinear surface tension term accurate drop formation can be predicted. The continuity and momentum equations in the transient form are integrated on an adaptive grid, conforming the jet and surface wave shape. The equations, which are parabolic in time and elliptic in space, are solved by a TVD scheme with characteristic flux splitting. The results of the present work are discussed and compared with available measurements and other analyses. The comparison shows that among the predictions, the current 1-D direct simulation results agree best with the experimental data. Furthermore, the computer time requirements are much (an order of magnitude) smaller than those of previously reported multidimensional analyses.
    Keywords: FLUID MECHANICS AND HEAT TRANSFER
    Type: AIAA PAPER 90-2066
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  • 8
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    Computational Fluid Dynamics Based Extraction of Heat Transfer Coefficient in Cryogenic Propellant Tanks (2015)
    In:  CASI
    Details
    Publication Date: 2019-07-19
    Description: Current reduced-order thermal model for cryogenic propellant tanks is based on correlations built for flat plates collected in the 1950's. The use of these correlations suffers from: inaccurate geometry representation; inaccurate gravity orientation; ambiguous length scale; and lack of detailed validation. The work presented under this task uses the first-principles based Computational Fluid Dynamics (CFD) technique to compute heat transfer from tank wall to the cryogenic fluids, and extracts and correlates the equivalent heat transfer coefficient to support reduced-order thermal model. The CFD tool was first validated against available experimental data and commonly used correlations for natural convection along a vertically heated wall. Good agreements between the present prediction and experimental data have been found for flows in laminar as well turbulent regimes. The convective heat transfer between tank wall and cryogenic propellant, and that between tank wall and ullage gas were then simulated. The results showed that commonly used heat transfer correlations for either vertical or horizontal plate over predict heat transfer rate for the cryogenic tank, in some cases by as much as one order of magnitude. A characteristic length scale has been defined that can correlate all heat transfer coefficients for different fill levels into a single curve. This curve can be used for the reduced-order heat transfer model analysis.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M15-4424 , AIAA/SAE/ASEE Joint Propulsion Conference; Jul 27, 2015 - Jul 29, 2015; Orlando, FL; United States
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  • 9
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    Validation of High-Resolution CFD Method for Slosh Damping Extraction of Baffled Tanks (2016)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The predicted slosh damping values from Loci-Stream-VOF agree with experimental data very well for all fill levels in the vicinity of the baffle. Grid refinement study is conducted and shows that the current predictions are grid independent. The increase of slosh damping due to the baffle is shown to arise from: a) surface breakup; b) cascade of energy from the low order slosh mode to higher modes; and c) recirculation inside liquid phase around baffle. The damping is a function of slosh amplitude, consistent with previous observation. Miles equation under predicts damping in the upper dome section.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M16-5417 , 2016 AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 25, 2016 - Jul 28, 2016; Salt Lake City, UT; United States
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  • 10
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    Prediction of Liquid Slosh Damping Using a High Resolution CFD Tool (2012)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Propellant slosh is a potential source of disturbance critical to the stability of space vehicles. The slosh dynamics are typically represented by a mechanical model of a spring mass damper. This mechanical model is then included in the equation of motion of the entire vehicle for Guidance, Navigation and Control analysis. Our previous effort has demonstrated the soundness of a CFD approach in modeling the detailed fluid dynamics of tank slosh and the excellent accuracy in extracting mechanical properties (slosh natural frequency, slosh mass, and slosh mass center coordinates). For a practical partially-filled smooth wall propellant tank with a diameter of 1 meter, the damping ratio is as low as 0.0005 (or 0.05%). To accurately predict this very low damping value is a challenge for any CFD tool, as one must resolve a thin boundary layer near the wall and must minimize numerical damping. This work extends our previous effort to extract this challenging parameter from first principles: slosh damping for smooth wall and for ring baffle. First the experimental data correlated into the industry standard for smooth wall were used as the baseline validation. It is demonstrated that with proper grid resolution, CFD can indeed accurately predict low damping values from smooth walls for different tank sizes. The damping due to ring baffles at different depths from the free surface and for different sizes of tank was then simulated, and fairly good agreement with experimental correlation was observed. The study demonstrates that CFD technology can be applied to the design of future propellant tanks with complex configurations and with smooth walls or multiple baffles, where previous experimental data is not available.
    Keywords: Fluid Mechanics and Thermodynamics
    Type: M12-1964 , 48th AIAA/ASME/SAE/ASEE Joint Propulsion Conference; Jul 29, 2012 - Aug 01, 2012; Atlanta, GA; United States
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