Further acceleration of multiscale simulation of rarefied gas flow via a generalized boundary treatment

Liu，Wei1,2; Zhang，Yanbing1; Zeng，Jianan1; Wu，Lei1

2024-04-15

10.1016/j.jcp.2024.112830

Journal of Computational Physics   影响因子和分区

0021-9991

1090-2716

The recently-developed general synthetic iterative scheme (GSIS) is efficient in simulating multiscale rarefied gas flows due to the coupling of mesoscopic kinetic equation and macroscopic synthetic equation: for linearized Poiseuille flow where the boundary flux is fixed at each iterative step, the steady-state solutions are found within dozens of iterations in solving the gas kinetic equations, while for general nonlinear flows the iteration number is increased by about one order of magnitude, caused by the incompatible treatment of the boundary flux for the macroscopic synthetic equation. In this paper, we propose a generalized boundary treatment (GBT) to further accelerate the convergence of GSIS. The main idea is, the truncated velocity distribution function at the boundary, similar to that used in the Grad 13-moment equation, is reconstructed by the macroscopic conserved quantities from the synthetic equation, as well as the high-order correction of non-equilibrium stress and heat flux from the kinetic equation; therefore, in each inner iteration solving the synthetic equation, the explicit constitutive relations facilitate real-time updates of the macroscopic boundary flux, driving faster information exchange in the flow field, and consequently achieving faster convergence. Moreover, the high-order correction derived from the kinetic equation can compensate the approximation by the truncation and ensure the boundary accuracy. The one-dimensional Fourier flow, two-dimensional hypersonic flow around a cylinder, three-dimensional pressure-driven pipe flow and the flow around the hypersonic technology vehicle are simulated. The accuracy of GSIS-GBT is validated by the direct simulation Monte Carlo method, the previous versions of GSIS, and the unified gas-kinetic wave-particle method. For the efficiency, in the near-continuum flow regime and slip regime, GSIS-GBT can be faster than the conventional iteration scheme in the discrete velocity method and the previous versions of GSIS by two- and one-order of magnitude, respectively.

Boltzmann kinetic equation Finite volume method General synthetic iterative scheme Hypersonic flow Low-speed internal flow Rarefied gas flow

SCI ; EI

英语

第一 ; 通讯

PHYSICS

2-s2.0-85184843678

Scopus

1.Department of Mechanics and Aerospace Engineering,Southern University of Science and Technology,Shenzhen,518055,China
2.Division of Emerging Interdisciplinary Areas,The Hong Kong University of Science and Technology,Clear Water Bay,Hong Kong

Liu，Wei,Zhang，Yanbing,Zeng，Jianan,et al. Further acceleration of multiscale simulation of rarefied gas flow via a generalized boundary treatment[J]. Journal of Computational Physics,2024,503.

Liu，Wei,Zhang，Yanbing,Zeng，Jianan,&Wu，Lei.(2024).Further acceleration of multiscale simulation of rarefied gas flow via a generalized boundary treatment.Journal of Computational Physics,503.

Liu，Wei,et al."Further acceleration of multiscale simulation of rarefied gas flow via a generalized boundary treatment".Journal of Computational Physics 503(2024).