A well-balanced unified gas-kinetic scheme for multiscale flow transport   under gravitational field

doi:10.1016/j.jcp.2016.12.022

CORC > 北京大学 > 工学院

	A well-balanced unified gas-kinetic scheme for multiscale flow transport under gravitational field
	Xiao, Tianbai ; Cai, Qingdong ; Xu, Kun
刊名	JOURNAL OF COMPUTATIONAL PHYSICS
	2017
关键词	Gravitational field Well-balanced property Unified gas-kinetic scheme Multi-scale flow Non-equilibrium phenomena RAREFIED FLOWS EQUATIONS CONTINUUM
DOI	10.1016/j.jcp.2016.12.022
英文摘要	The gas dynamics under gravitational field is usually associated with multiple scale nature due to large density variation and a wide variation of local Knudsen number. It is challenging to construct a reliable numerical algorithm to accurately capture the non equilibrium physical effect in different regimes. In this paper, a well-balanced unified gas-kinetic scheme (UGKS) for all flow regimes under gravitational field will be developed, which can be used for the study of non-equilibrium gravitational gas system. The well-balanced scheme here is defined as a method to evolve an isolated gravitational system under any initial condition to a hydrostatic equilibrium state and to keep such a solution. To preserve such a property is important for a numerical scheme, which can be used for the study of slowly evolving gravitational system, such as the formation of star and galaxy. Based on the Boltzmann model with external forcing term, the UGKS uses an analytic time-dependent (or scale-dependent) solution in the construction of the discretized fluid dynamic equations in the cell size and time step scales, i.e., the so-called direct modeling method. As a result, with the variation of the ratio between the numerical time step and local particle collision time, the UGKS is able to recover flow physics in different regimes and provides a continuous spectrum of gas dynamics. For the first time, the flow physics of a gravitational system in the transition regime can be studied using the UGKS, and the non-equilibrium phenomena in such a gravitational system can be clearly identified. Many numerical examples will be used to validate the scheme. New physical observation, such as the correlation between the gravitational field and the heat flux in the transition regime, will be presented. The current method provides an indispensable tool for the study of non equilibrium gravitational system. (C) 2016 Elsevier Inc. All rights reserved.; Hong Kong Research Grant Council [16207715, 16211014, 620813]; National Science Foundation of China [91330203, 91530319]; SCI(E); ARTICLE; 475-491; 332
语种	英语
内容类型	期刊论文
源URL	[http://ir.pku.edu.cn/handle/20.500.11897/474989]
专题	工学院
推荐引用方式 GB/T 7714	Xiao, Tianbai,Cai, Qingdong,Xu, Kun. A well-balanced unified gas-kinetic scheme for multiscale flow transport under gravitational field[J]. JOURNAL OF COMPUTATIONAL PHYSICS,2017.
APA	Xiao, Tianbai,Cai, Qingdong,&Xu, Kun.(2017).A well-balanced unified gas-kinetic scheme for multiscale flow transport under gravitational field.JOURNAL OF COMPUTATIONAL PHYSICS.
MLA	Xiao, Tianbai,et al."A well-balanced unified gas-kinetic scheme for multiscale flow transport under gravitational field".JOURNAL OF COMPUTATIONAL PHYSICS (2017).