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Related papers: Unified Gas-kinetic Wave-Particle Methods II: Mult…

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The unified gas-kinetic wave-particle (UGKWP) method is proposed for the neutron transport equation, addressing the inherent multiscale nature of neutron propagation in both optically thin and thick regimes. UGKWP couples macroscopic…

Numerical Analysis · Mathematics 2025-09-15 Guangwei Liu , Shuang Tan , Yanli Wang

A unified gas kinetic scheme (UGKS) for multi-scale and multi-component plasma transport is constructed. The current scheme is a direct modeling method, where the time evolution solutions from the Vlasov-BGK equations of electron and ion…

Computational Physics · Physics 2017-12-21 Chang Liu , Kun Xu

The unified gas-kinetic wave-particle method (UGKWP) has been developed for the multiscale gas, plasma, and multiphase flow transport processes for the past years. In this work, we propose an implicit unified gas-kinetic wave-particle…

Computational Physics · Physics 2023-09-22 Chang Liu , Weiming Li , Peng Song , Kun Xu

Fluid dynamic equations are valid in their respective modeling scales. With a variation of the modeling scales, theoretically there should have a continuous spectrum of fluid dynamic equations. In order to study multiscale flow evolution…

Numerical Analysis · Mathematics 2017-12-21 Chang Liu , Kun Xu , Quanhua Sun , Qingdong Cai

The Unified Gas-Kinetic Wave-Particle (UGKWP) method, developed for multiscale simulation of partially ionized plasmas, has been extended to unstructured meshes, enabling the modeling of electromagnetic flows around a hemisphere across…

Plasma Physics · Physics 2026-04-29 Zhigang Pu , Kun Xu

In this paper, we extend the unified kinetic particle (UGKP) method to the frequency-dependent radiative transfer equation with both absorption-emission and scattering processes. The extended UGKP method could not only capture the diffusion…

Computational Physics · Physics 2023-02-17 Yuan Hu , Chang Liu

In this paper, a unified gas kinetic scheme for multiphase dilute gas-particle system is proposed. The UGKS multiphase (UGKS-M) is a finite volume method, which captures flow physics in the regimes from collisionless multispecies transport…

Computational Physics · Physics 2019-05-01 Chang Liu , Zhao Wang , Kun Xu

In this paper, a unified gas-kinetic scheme (UGKS) with simplified multi-scale numerical flux is proposed for the thermodynamic non-equilibrium flow simulation involving the excitation of molecular vibrational degrees of freedom in all flow…

Fluid Dynamics · Physics 2023-02-08 Rui Zhang , Sha Liu , Chengwen Zhong , Congshan Zhuo

The unified gas kinetic scheme (UGKS) is a direct modeling method based on the gas dynamical model on the mesh size and time step scales. With the implementation of particle transport and collision in a time-dependent flux function, the…

Computational Physics · Physics 2017-10-25 Yajun Zhu , Chengwen Zhong , Kun Xu

In this work, we present a unified gas-kinetic particle (UGKP) method for the simulation of multiscale photon transport. The multiscale nature of the particle method mainly comes from the recovery of the time evolution flux function in the…

Computational Physics · Physics 2018-10-16 Weiming Li , Chang Liu , Yajun Zhu , Jiwei Zhang , 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

This paper presents two novel methods for solving multi-scale phonon transport problems with dispersion and polarization effects: the unified gas-kinetic wave-particle (UGKWP) method and the implicit unified gas-kinetic particle (IUGKP)…

Computational Physics · Physics 2025-06-23 Hongyu Liu , Xiaojian Yang , Chuang Zhang , Xing Ji , Kun Xu

Multiscale non-equilibrium physics at large variations of local Knudsen number are encountered in applications of aerospace engineering and micro-electro-mechanical systems, such as high-speed flying vehicles and low pressure of the…

Fluid Dynamics · Physics 2023-12-06 Yufeng Wei , Wenpei Long , Kun Xu

Reactive flows for rarefied gas mixtures involve a multi-scale transport characterized by particle collisions and free streaming, and non-equilibrium physics containing multi-species interactions, and chemical non-equilibrium. These flows…

Fluid Dynamics · Physics 2024-12-16 Yufeng Wei , Junzhe Cao , Kun Xu

The gas dynamics under gravitational field is usually associated with the multiple scale nature due to large density variation and a wide range of local Knudsen number. It is chal- lenging to construct a reliable numerical algorithm to…

Computational Physics · Physics 2017-02-01 Tianbai Xiao , Qingdong Cai , Kun Xu

In this paper, a unified gas kinetic scheme with adaptive velocity space (AUGKS) for multiscale flow transport will be developed. In near-equilibrium flow regions, particle distribution function is close to the Chapman-Enskog expansion and…

Computational Physics · Physics 2018-02-15 Tianbai Xiao , Kun Xu , Qingdong Cai

This paper proposes a unified gas-kinetic particle (UGKP) method for the frequency-dependent photon transport process. The photon transport is a typical multiscale process governed by the nonlinear radiative transfer equations (RTE). The…

Numerical Analysis · Mathematics 2023-01-18 Weiming Li , Chang Liu , Peng Song

Simulating multiscale flows with moving boundaries, such as hypersonic multi-body separation and flows in micro-electro-mechanical systems (MEMS), requires robust numerical methods that couple mesh deformation with complex flow physics.…

Fluid Dynamics · Physics 2026-04-14 Yue Zhang , Wenpei Long , Junzhe Cao , Kun Xu

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

The discrete unified gas kinetic scheme (DUGKS) is a new finite volume (FV) scheme for continuum and rarefied flows which combines the benefits of both Lattice Boltzmann Method (LBM) and unified gas kinetic scheme (UGKS). By reconstruction…

Computational Physics · Physics 2024-05-29 Mingliang Zhong , Sen Zou , Dongxin Pan , Congshan Zhuo , Chengwen Zhong