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We study hypocoercivity for a class of linear and linearized BGK models for discrete and continuous phase spaces. We develop methods for constructing entropy functionals that prove exponential rates of relaxation to equilibrium. Our…

Analysis of PDEs · Mathematics 2023-08-21 Franz Achleitner , Anton Arnold , Eric A. Carlen

Kinetic models of polyatomic gas typically account for the internal degrees of freedom at the level of the two-particle distribution function. However, close to the hydrodynamic limit, the internal (rotational) degrees of freedom tend to be…

Fluid Dynamics · Physics 2023-05-24 Praveen Kumar Kolluru , Mohammad Atif , Santosh Ansumali

The Boltzmann equation describes the detailed microscopic behaviour of a dilute gas, and represents the basis of the kinetic theory of gases. In order to reduce the difficulties in solving the Boltzmann equation, simple expressions of a…

Mathematical Physics · Physics 2018-12-06 Armando Majorana

In this article we focus on kinetic equations for gas mixtures since in applications one often has to deal with mixtures instead of a single gas. In particular we consider an approximation of the Boltzmann equation, the…

Analysis of PDEs · Mathematics 2022-03-30 Marlies Pirner , Sandra Warnecke

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

Abstracet: We present a new thermal lattice BGK model in D-dimensional space for the numerical calculation of fluid dynamics. This model uses a higher order expansion of equilibrium distribution in Maxwellian type. In the mean time the…

comp-gas · Physics 2008-02-03 Yu Chen , Hirotada Ohashi , Mamoru Akiyama

In this paper, we propose a general framework to design asymptotic preserving schemes for the Boltzmann kinetic kinetic and related equations. Numerically solving these equations are challenging due to the nonlinear stiff collision (source)…

Numerical Analysis · Mathematics 2015-05-13 Francis Filbet , S. Jin

We propose a numerical approach, of the BGK kinetic type, that is able to approximate with a given, but arbitrary, order of accuracy the solution of linear and non-linear convection-diffusion type problems: scalar advection-diffusion,…

Numerical Analysis · Mathematics 2023-10-13 Gauthier Wissocq , Rémi Abgrall

We study hypocoercivity for a class of linearized BGK models for continuous phase spaces. We develop methods for constructing entropy functionals that enable us to prove exponential relaxation to equilibrium with explicit and physically…

Analysis of PDEs · Mathematics 2023-08-21 Franz Achleitner , Anton Arnold , Eric A. Carlen

We study spatially non-homogeneous kinetic models for vehicular traffic flow. Classical formulations, as for instance the BGK equation, lead to unconditionally unstable solutions in the congested regime of traffic. We address this issue by…

Physics and Society · Physics 2019-07-22 Michael Herty , Gabriella Puppo , Sebastiano Roncoroni , Giuseppe Visconti

In this paper, we study the Cauchy problem of the linearized kinetic equations for the models of Marle and Anderson-Witting, and compare these dispersion relations with the 14-moment theory. First, we propose a modification of the Marle…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Makoto Takamoto , Shu-ichiro Inutsuka

In [Phys. Rev. 94 (1954), 511-525], P.L. Bhatnagar, E.P. Gross and M. Krook introduced a kinetic equation (the BGK equation), effective in physical situations where the Knudsen number is small compared to the scales where Boltzmann's…

Mathematical Physics · Physics 2023-07-25 Paolo Buttà , Mario Pulvirenti , Sergio Simonella

Solving the Bhatnagar-Gross-Krook (BGK) equation with a stochastic particle approach enables efficient and flexible simulations of flows in the transition regime, between continuum and free molecular flow. However, the usual first-order…

Fluid Dynamics · Physics 2024-12-02 Marcel Pfeiffer , Félix Garmirian , Tobias Ott

In this paper, we consider the existence problem for a stationary relaxational models of the quantum Boltzmann equation. More precisely, we establish the existence of mild solution to the fermionic or bosonic quantum BGK model in a slab…

Analysis of PDEs · Mathematics 2020-01-29 Gi-Chan Bae , Seok-Bae Yun

This note is devoted to a simple method for proving hypocoercivity of the solutions of a kinetic equation involving a linear time relaxation operator, i.e. the construction of an adapted Lyapunov functional satisfying a Gronwall-type…

Analysis of PDEs · Mathematics 2009-12-07 Jean Dolbeault , Clément Mouhot , Christian Schmeiser

For the first time, the non-equilibrium time-relaxation kinetic model (NTRKM) is proposed for compressible turbulence modeling on unresolved grids. Within the non-equilibrium time-relaxation framework, NTRKM is extended in the form of…

Fluid Dynamics · Physics 2021-12-17 Guiyu Cao , Liang Pan , Kun Xu , Minping Wan , Shiyi Chen

The kinetic theory of a self-gravitating system is considered in the framework of Bhatnager-Gross-Krook model. This approach offers a unique and tractable setup for studying the central, collision-dominated region of the system, as well as…

Statistical Mechanics · Physics 2007-05-23 A. E. Allahverdyan , Th. M. Nieuwenhuizen

We present a general, high-order, fully explicit relaxation scheme which can be applied to any system of nonlinear hyperbolic conservation laws in multiple dimensions. The scheme consists of two steps. In a first (relaxation) step, the…

Numerical Analysis · Mathematics 2016-09-06 Pauline Lafitte , Ward Melis , Giovanni Samaey

In dilute gas kinetic theory, model collision dynamics such as Bhatnagar-Gross-Krook (BGK) model is often used to get a better insight and numerical modelling. BGK model and its variants assume that highly nonlinear collision term can be…

Statistical Mechanics · Physics 2020-08-26 Samarth Agrawal , S. K. Singh , Santosh Ansumali

In this paper, we develop a family of third order asymptotic-preserving (AP) and asymptotically accurate (AA) diagonally implicit Runge-Kutta (DIRK) time discretization methods for the stiff hyperbolic relaxation systems and kinetic…

Numerical Analysis · Mathematics 2021-05-10 Mingchang Ding , Jing-Mei Qiu , Ruiwen Shu