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Related papers: A BGK model for high temperature rarefied gas flow…

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This minicourse contains a description of recent results on the modelling of rarefied gases in weakly non equilibrium regimes, and the numerical methods used to approximate the resulting equations. Therefore this work focuses on BGK type…

Computational Physics · Physics 2019-02-25 Gabriella Puppo

The thermal lattice BGK model is a recently suggested numerical tool which aims to simulate thermohydrodynamic problems. We investigate the quality of the lattice BGK simulation by calculating the temperature profiles in the Couette flow…

comp-gas · Physics 2009-10-22 Y. Chen , H. Ohashi , M. Akiyama

In this paper we present a numerical scheme to simulate a moving rigid body with arbitrary shape suspended in a rarefied gas. The rarefied gas is simulated by solving the Boltzmann equation using a DSMC particle method. The motion of the…

Computational Physics · Physics 2015-06-22 Samir Shrestha , Sudarshan Tiwari , Axel Klar , Steffen Hardt

Hypersonic flow around a vehicle in near space flight is associated with multiscale non-equilibrium physics at a large variation of local Knudsen number from the leading edge highly compressible flow to the trailing edge particle free…

Fluid Dynamics · Physics 2022-11-28 Yufeng Wei , Yajun Zhu , Kun Xu

The non-equilibrium gas dynamics is described by the Boltzmann equation, which can be solved numerically through the deterministic and stochastic methods. Due to the complicated collision term of the Boltzmann equation, many kinetic…

Computational Physics · Physics 2021-02-03 Xiaocong Xu , Yipei Chen , Kun Xu

We consider the socalled Bathnagar-Gross-Krook (BGK) model, an approximation of the Boltzmann equation, describing the time evolution of a single momoatomic rarefied gas and satisfying the same two main properties (conservation properties…

Analysis of PDEs · Mathematics 2021-10-26 Marlies Pirner

n an early approach, we proposed a kinetic model with multiple translational temperature [K. Xu, H. Liu and J. Jiang, Phys. Fluids {\bf 19}, 016101 (2007)], to simulate non-equilibrium flows. In this paper, instead of using three…

Fluid Dynamics · Physics 2008-03-13 Kun Xu , Zhaoli Guo

We calculate in this work the Navier-Stokes transport coefficients from the Boltzmann equation for $d$-dimensional inelastic Maxwell models. By granular gas we mean here a low density system of identical spheres that lose a fraction of…

Statistical Mechanics · Physics 2015-06-18 Moisés G. Chamorro , Vicente Garzó , Francisco Vega Reyes

Multi-species BGK models describe the dynamics of rarefied gases with constituent particles of different elements or compounds with potentially non-trivial velocity distributions. In this paper, moment equations for the bulk velocities,…

Mathematical Physics · Physics 2023-10-20 Evan Habbershaw , Ryan S. Glasby , Jeffrey R. Haack , Cory D. Hauck , Steven M. Wise

We propose a BGK-type kinetic model for relativistic reactive gas mixtures. This model serves as a computationally tractable yet physically consistent alternative to the corresponding Boltzmann equation. The relaxation operator is…

Analysis of PDEs · Mathematics 2025-09-03 Seung-Yeon Cho , Byung-Hoon Hwang , Myeong-Su Lee , Seok-Bae Yun

In this paper we present a novel technique for the simulation of moving boundaries and moving rigid bodies immersed in a rarefied gas using an Eulerian-Lagrangian formulation based on least square method. The rarefied gas is simulated by…

Numerical Analysis · Mathematics 2022-03-23 Sudarshan Tiwari , Axel Klar , Giovanni Russo

A steady state of a granular gas with homogeneous granular temperature, no mass flow, and nonzero heat flux is studied. The state is created by applying an external position--dependent force or by enclosing the grains inside a curved…

Statistical Mechanics · Physics 2016-10-31 Nagi Khalil

Kinetic models for polyatomic gases have two temperatures for the two different types of degrees of freedom, the translational and the internal energy degrees of freedom. Therefore, in the case of BGK models one expects two types of…

Analysis of PDEs · Mathematics 2018-10-23 Marlies Pirner

Kinetic models based on the Bhatnagar-Gross-Krook (BGK) framework provide an efficient alternative to the Boltzmann equation for rarefied gas flows; however, existing formulations for gas mixtures remain limited in representing…

Fluid Dynamics · Physics 2026-04-28 Inchan Kim , Joonbeom Kim , Woonghwi Park , Eunji Jun

We describe an asymptotic procedure for deriving continuum equations from the kinetic theory of a simple gas. As in the works of Hilbert, of Chapman and of Enskog, we expand in the mean flight time of the constituent particles of the gas,…

Astrophysics · Physics 2009-11-06 Xinzhong Chen , Hongling Rao , Edward A. Spiegel

We study the Bathnagar-Gross-Krook (BGK) equation in a smooth bounded domain featuring a diffusive reflection boundary condition with general collision frequency. We prove that the BGK equation admits a unique global solution with an…

Analysis of PDEs · Mathematics 2026-01-09 Hongxu Chen , Christian Klingenberg , Marlies Pirner

We consider two models for a two component gas mixture with translational and internal energy degrees of freedom described by a BGK approximation assuming that the number of particles of each species remains constant. The two species are…

Analysis of PDEs · Mathematics 2018-06-29 Marlies Pirner

A peculiarity of the hydrodynamic Navier-Stokes equations for a granular gas is the modification of the Fourier law, with the presence of an additional contribution to the heat flux that is proportional to the density gradient.…

Statistical Mechanics · Physics 2015-06-11 J. Javier Brey , M. J. Ruiz-Montero

We propose a BGK-type kinetic model for a binary gas mixture, designed to serve as a kinetic formulation of compressible two-phase fluid dynamics. The model features species-dependent adiabatic exponents, and the relaxation operator is…

Analysis of PDEs · Mathematics 2025-06-25 Seung Yeon Cho , Young-Pil Choi , Byung-Hoon Hwang , Sihyun Song

We present a numerical comparison between two standard finite volume schemes and a discontinuous Galerkin method applied to the BGK equation of rarefied gas dynamics. We pay a particular attention to the numerical boundary conditions in…

Numerical Analysis · Mathematics 2020-03-13 Céline Baranger , Nicolas Hérouard , Julien Mathiaud , Luc Mieussens