Development of Continuum Onset Criteria with Direct Simulation Monte-Carlo Using Boltzmann's H-Theorem: Review and Vision

Camberos, José; Schrock, Christopher R.; McMullan, Richard J.; Branam, Richard

doi:10.2514/6.2006-2942

Cited by 13 publications

(9 citation statements)

References 16 publications

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“…The areas of the flow in which the continuum hypothesis breaks down (or equivalently, in which the flow is no longer in local thermodynamic equilibrium) can be quantified by the use of a continuum breakdown parameter. Although there have been several breakdown parameters presented in the literature [2][3][4][5], the one that appears to be most appropriate for hypersonic compressible flows is the gradient-length local (GLL) Knudsen number [6,7]:…”

Section: Introductionmentioning

confidence: 99%

Velocity Slip and Temperature Jump in Hypersonic Aerothermodynamics

Lofthouse

Scalabrin

Boyd

2008

Journal of Thermophysics and Heat Transfer

119

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Hypersonic vehicles experience different flow regimes during flight due to changes in atmospheric density. Computational fluid dynamics, although relatively computationally inexpensive, is not physically accurate in areas of highly nonequilibrium flows. The direct simulation Monte Carlo method, although physically accurate for all flow regimes, is relatively computationally expensive. In a continuing effort to understand the performance of computational fluid dynamics and direct simulation Monte Carlo in hypersonic flows, the current study investigates the effect of continuum breakdown on surface aerothermodynamic properties (pressure, shear stress, and heat transfer rate) of a cylinder in Mach-10 and Mach-25 flows of argon gas for several different flow regimes, from the continuum to a rarefied gas. Several different velocity-slip and temperature-jump boundary conditions are examined for use with the computational fluid dynamics method. Computational fluid dynamics and direct simulation Monte Carlo solutions are obtained at each condition. Total drag and peak heat transfer rate predictions by computational fluid dynamics remain within about 6% of the direct simulation Monte Carlo predictions for all regimes considered, with the Gökçen-type slip condition giving the best results.

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Section: Introductionmentioning

confidence: 99%

Velocity Slip and Temperature Jump in Hypersonic Aerothermodynamics

Lofthouse

Scalabrin

Boyd

2008

Journal of Thermophysics and Heat Transfer

119

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“…(21) seems to suggest that the use of a leading coefficient similar to (M + 1) may be an effective means of improving on the reliability or generality of some existing gradient-based breakdown parameters. However, as emphasized in a number of studies, 3,19,24 all gradient-based parameters are limited by inherent approximations and assumptions, and these parameters can at best provide only a rough indication of the existence or degree of continuum breakdown. It should also be noted that some threshold value, corresponding to a given level of disagreement between continuum and nonequilibrium solutions, should ideally be determined for any new parameter in order to reliably use this parameter for breakdown evaluation.…”

Section: Characteristics Of Proposed Modificationmentioning

confidence: 99%

Continuum Breakdown Effects on Surface Properties for Hypersonic Shock Wave-Boundary Layer Interaction

Burt

Josyula

2013

44th AIAA Thermophysics Conference

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Shock wave-boundary layer interaction (SWBLI) on the surface of hypersonic vehicles can lead to large surface-heating spikes which in turn impact vehicle design or flight envelopes. Accurate determination of SWBLI effects is therefore a potentially important element of hypersonic vehicle design, and high fidelity numerical modeling of SWBLI provides key advantages in the vehicle design cycle. One of the difficulties in hypersonic SWBLI simulation is the influence of continuum breakdown phenomena; such phenomena have been well documented for strong shocks and hypersonic boundary layers, but not specifically for SWBLI. In this work, we address various limitations in current engineering approaches for identification of continuum breakdown relevant to SWBLI flow problems. In particular, we present a new continuum breakdown criterion based on surface quantities which are determined using kinetic simulation techniques. A modification is then proposed to existing gradient-based breakdown criteria in order to resolve an inconsistency in Mach number dependence. The proposed breakdown criteria are assessed through comparison with an established criterion for a set of representative flat plate SWBLI problems, and for a type IV shock-shock interaction problem involving oblique shock impingement on the detached bow shock over a cylinder. This work is intended to demonstrate connections between continuum breakdown and gas properties along a surface, to reconsider Mach number dependence for gradient-based breakdown evaluation, and to determine the extent of continuum breakdown associated with SWBLI under representative hypersonic conditions.

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“…In general, such techniques are either intended only for limited types of flows and certain modes of nonequilibrium [18,19], or are very computationally expensive and inappropriate for use in simulation methods which include near-equilibrium assumptions [20]. A comparative analysis of different breakdown criteria is out of the scope of the present study, and the reader is referred to an extensive body of existing research on this topic [11,12,14,[18][19][20]. For the hybrid algorithm presented here, a relatively simple and conservative technique is therefore proposed.…”

Section: Continuum Breakdown and Cell Assignmentmentioning

confidence: 99%