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In order to further enhance the computational efficiency of the implicit unified gas-kinetic scheme (IUGKS, JCP 315 (2016) 16-38) for multi-scale flow simulation, a two-step IUGKS is proposed in this paper. The multiscale solution of the…

Computational Physics · Physics 2021-05-04 Xiaocong Xu , Yajun Zhu , Chang Liu , Kun Xu

In the study of gas dynamics, theoretical modeling and numerical simulation are mostly set up with deterministic settings. Given the coarse-grained modeling in theories of fluids, considerable uncertainties may exist between flow-field…

Computational Physics · Physics 2020-08-07 Tianbai Xiao

The gas-kinetic scheme (GKS) provides high computational efficiency and accuracy for continuum flow simulations but is unable to reliably capture rarefaction effects. In contrast, although the discrete velocity method (DVM) is better suited…

Fluid Dynamics · Physics 2026-05-08 Hangkong Wu , Yuze Zhu , Yajun Zhu , Kun Xu

In the study of rarefied gas dynamics, the discrete velocity method (DVM) has been widely employed to solve the gas kinetic equations. Although various versions of DVM have been developed, their performance, in terms of accuracy and…

Fluid Dynamics · Physics 2016-12-21 Peng Wang , Minh-Tuan Ho , Lei Wu , Zhaoli Guo , Yonghao Zhang

This paper introduces a time-domain harmonic balance unified gas-kinetic scheme (HB-UGKS) designed to simulate temporally periodic flows across all Knudsen regimes. The harmonic balance approach reformulates the periodic problem into a…

Fluid Dynamics · Physics 2026-05-06 Yuze Zhu , Hangkong Wu , Yufeng Wei , Kun Xu

The Gas-Kinetic Scheme (GKS), widely used in computational fluid dynamics for simulating hypersonic and other complicated flow phenomena, is extended in this work to electromagnetic problems by solving Maxwell's equations. In contrast to…

Numerical Analysis · Mathematics 2026-01-01 Zhigang Pu , Wenpei Long , Kun Xu

In this work, we extend the discrete unified gas-kinetic scheme (DUGKS) [Guo et al., Phys. Rev. E 88, 033305 (2013)] to continue two-phase flows. In the framework of DUGKS, two kinetic model equations are used to solve the…

Computational Physics · Physics 2018-10-02 Chunhua Zhang , Kang Yang , Zhaoli Guo

In this paper, the original discrete unified gas kinetic scheme (DUGKS) is extended to arbitrary Lagrangian-Eulerian (ALE) framework for simulating the low-speed continuum and rarefied flows with moving boundaries. For ALE method, the mesh…

Computational Physics · Physics 2020-01-08 Yong Wan , Chengwen Zhong

In this paper, authors focus effort on improving the conventional discrete velocity method (DVM) into a multiscale scheme in finite volume framework for gas flow in all flow regimes. Unlike the typical multiscale kinetic methods unified…

Computational Physics · Physics 2020-03-24 Ruifeng Yuan , Sha Liu , Chengwen Zhong

When the flow is sufficiently rarefied, a temperature gradient, for example, between two walls separated by a few mean free paths, induces a gas flow---an observation attributed to the thermo-stress convection effects at microscale. The…

This paper is a continuation of our earlier work [Z.L. Guo {\it et al.}, Phys. Rev. E {\bf 88}, 033305 (2013)] where a multiscale numerical scheme based on kinetic model was developed for low speed isothermal flows with arbitrary Knudsen…

Fluid Dynamics · Physics 2015-06-22 Zhaoli Guo , Ruijie Wang , Kun Xu

The simulation of rarefied gas flow based on the Boltzmann equation is challenging, especially when the gas mixtures have disparate molecular masses. In this paper, a computationally tractable kinetic model is proposed for monatomic gas…

Fluid Dynamics · Physics 2024-03-12 Qi Li , Jianan Zeng , Lei Wu

We study efficient simulation of steady state for rarefied gas flow, which is modeled by the Boltzmann equation with BGK-type collision term. A nonlinear multigrid solver is proposed to resolve the efficiency issue by the following…

Numerical Analysis · Mathematics 2022-06-28 Zhicheng Hu , Guanghan Li

Simulating complex gas flows from turbulent to rarefied regimes is a long-standing challenge, since turbulence and rarefied flow represent contrasting extremes of computational aerodynamics. We propose a multiscale method to bridge this…

Fluid Dynamics · Physics 2024-08-16 Songyan Tian , Lei Wu

The general characteristics based off-lattice Boltzmann scheme (BKG) proposed by Bardow et~al.(2006), and the discrete unified gas kinetic scheme (DUGKS) are two methods that successfully overcome the time step restriction by the collision…

Fluid Dynamics · Physics 2015-11-23 Lianhua Zhu , Peng Wang , Zhaoli Guo

Over the past 7 decades, the classical Monte Carlo method has played a huge role in the fields of rarefied gas flow and micro/nano scale heat transfer, but it also has shortcomings: the time step and cell size are limited by the relaxation…

Computational Physics · Physics 2025-05-15 Hongyu Liu , Xiaojian Yang , Chuang Zhang , Xing Ji , Kun Xu

An efficient third-order discrete unified gas kinetic scheme (DUGKS) with efficiency is presented in this work for simulating continuum and rarefied flows. By employing two-stage time-stepping scheme and the high-order DUGKS flux…

Fluid Dynamics · Physics 2018-02-28 Chen Wu , Chang Shu , Baochang Shi , Zhen Chen

A general framework for constructing discrete Boltzmann model for non-equilibrium flows based on the Shakhov model is presented. The Hermite polynomial expansion and a set of discrete velocity with isotropy are adopted to solve the kinetic…

Fluid Dynamics · Physics 2019-03-27 Yudong Zhang , Aiguo Xu , Guangcai Zhang , Zhihua Chen , Pei Wang

The multi-frequency radiation transport equation (RTE) system models the photon transport and the energy exchange process between the background material and different frequency photons. In this paper, the unified gas-kinetic wave-particle…

Computational Physics · Physics 2023-12-29 Xiaojian Yang , Yajun Zhu , Chang Liu , Kun Xu

This study extends the Unified Gas-Kinetic Scheme (UGKS) and the Unified Gas-Kinetic Wave-Particle (UGKWP) method for electrostatic plasma modeling, ensuring the correct asymptotic limits with respect to both the Debye length and the mean…

Computational Physics · Physics 2025-12-18 Zhigang Pu , Kun Xu