Detailed Analysis of a Hybrid CFD-DSMC Method for Hypersonic Non-Equilibrium Flows

Schwartzentruber, Thomas E.; Boyd, Iain D.

doi:10.2514/6.2005-4829

Cited by 6 publications

(5 citation statements)

References 17 publications

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“…Development of such hybrid methods is an area of active research. 3,4 For near continuum flows, the CFD method would be used in the majority of the flow field while DSMC would be used in the shock and the wake regions.…”

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confidence: 99%

Effects of Continuum Breakdown on Hypersonic Aerothermodynamics

Lofthouse

Boyd

Wright

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

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Hypersonic vehicles experience different flow regimes during flight due to changes in atmospheric density. Hybrid Computational Fluid Dynamics (CFD) and Direct Simulation Monte Carlo (DSMC) methods are developed to simulate the flow in different hypersonic regimes. These methods use a breakdown parameter to determine regions of the flow where the CFD physics are no longer valid. The current study investigates the effect of continuum breakdown on surface properties, such as pressure, shear stress and heat transfer rate, on a cylinder in a Mach 10 flow of argon gas for several different flow regimes, from the continuum to a rarefied gas. The difference in total drag ranges from 0.5% for a continuum to 26.2% for a rarefied gas. Peak heat transfer rate differences ranges from nearly 4% for a continuum to almost 32% for a rarefied gas. Drag depends primarily on continuum breakdown in the wake, while heat transfer rate appears to depend primarily on continuum breakdown in the shock and differences in thermal boundary layer thickness. I. Introduction A hypersonic vehicle such as a planetary entry capsule or a reusable launch vehicle, will experience vastly different flow regimes during the course of its flight trajectory because the earth's atmosphere varies in density as a function of altitude. Reproduction of these varied flow conditions in ground-based laboratory facilities is both expensive and technically challenging. Hence, there is an extremely important role for computational models in the development of hypersonic vehicles.

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confidence: 99%

Effects of Continuum Breakdown on Hypersonic Aerothermodynamics

Lofthouse

Boyd

Wright

2006

44th AIAA Aerospace Sciences Meeting and Exhibit

Self Cite

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“…Papp et al 30 developed an automated arbitrary breakdown surface generation procedure for the hybrid continuum CFD/DSMC approach and applied it to simulate the high altitude plume flow fields of continuum/non-continuum coupling problems. CFD/DSMC methods [31][32][33] address the shortcomings of single-model methods, but the exchange of information at the junction is difficult. Therefore, seeking a unified algorithm that directly connects the continuum flow to the rarefaction flow and can effectively simulate the aerodynamic problems of various regimes is a problem that the academic circles at home and abroad have wanted to solve.…”

Section: Introductionmentioning

confidence: 99%

Gas‐kinetic unified algorithm for two‐dimensional planar and axisymmetric nozzle flows

Jiang

et al. 2023

Numerical Methods in Fluids

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SummaryFor high‐altitude nozzle or micronozzle flows and other gas flows in the slip or transition flow regime, how to solve it reliably has always been a difficult problem. In this paper, a unified gas kinetic expression is presented to describe the two‐dimensional planar and the axisymmetric nozzle flows, and the computable modeling of the Boltzmann equation is developed at the first time for the nozzle flows by introducing the gas molecular collision relaxing parameter and the local equilibrium distribution function integrated in the unified expression with the flow state controlling parameter, including the macroscopic flow variables, the gas viscosity transport coefficient, the thermodynamic effect, the molecular power law, and molecular models, covering a full spectrum of flow regimes. The boundary conditions involved in the nozzle flow have been mathematically expressed at the level of the gas molecular velocity distribution function, and the model equations have been solved uniformly by the gas‐kinetic unified algorithm (GKUA) for rarefied transition to continuum flows. The presented simulated results from the test cases show promising of simulating gas flow from transitional flow to continuum flow in the same flow domain, especially for those flow involving low‐speed gas flow in rarefied regime, which is otherwise practically difficult using direct simulation Monte Carlo (DSMC).

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“…The Poisson equation, being a time-independent equation, can be solved efficiently using a steadystate FDM approach rather than the transient LBM approach. Such a hybridization of schemes has been reported for coupled nonlinear simulations and is often applied for problems with a large difference in length scales, as in aerodynamics and climate science, to increase computational efficiency [41][42][43][44]. Also, at the micro-scale, hybrid schemes have been successfully applied for problems like emulsification and heat transfer with surfactants [45][46][47].…”

Section: Introductionmentioning

confidence: 99%

A fully coupled hybrid lattice Boltzmann and finite difference method-based study of transient electrokinetic flows

2020

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Transient electrokinetic (EK) flows involve the transport of conductivity gradients developed as a result of mixing of ionic species in the fluid, which in turn is affected by the electric field applied across the channel. The presence of three different coupled equations with corresponding different time scales makes it difficult to model the problem using the lattice Boltzmann method (LBM). The present work aims to develop a hybrid LBM and finite difference method (FDM)-based model which can be used to study the electro-osmotic flows (EOFs) and the onset of EK instabilities using an Ohmic model, where fluid and conductivity transport are solved using LBM and the electric field is solved using FDM. The model developed will be used to simulate three different problems: (i) EOF with varying zeta-potential on the wall, (ii) similitude in EOF, and (iii) EK instabilities due to the presence of conductivity gradients. Problems (i) and (ii) will be compared with the analytical results and problem (iii) will be compared with the simulations of a spectral method-based numerical model. The results obtained from the present simulations will show that the developed model is capable of studying transient EK flows and of predicting the onset of instability.

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Detailed Analysis of a Hybrid CFD-DSMC Method for Hypersonic Non-Equilibrium Flows

Cited by 6 publications

References 17 publications

Effects of Continuum Breakdown on Hypersonic Aerothermodynamics

Effects of Continuum Breakdown on Hypersonic Aerothermodynamics

Gas‐kinetic unified algorithm for two‐dimensional planar and axisymmetric nozzle flows

A fully coupled hybrid lattice Boltzmann and finite difference method-based study of transient electrokinetic flows

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