277 citations · 756 across the 24 of their papers we have counts for
27 papers
An implicit multiscale solver for steady kinetic equations based on wave-particle decomposition
Chang Liu, Kun Xu
Steady kinetic computations require accurate transport on meshes that do not resolve the mean free path and efficient removal of slowly decaying macroscopic errors. We develop a cl…
Wave-Particle Decomposition for Kinetic Equations II: Full Boltzmann equation
Chang Liu, Kun Xu
The wave-particle decomposition of kinetic relaxation equations is extended to the full Boltzmann equation. An identity transformation writes the collision term as a relaxation tow…
A wave-particle decomposition framework for multiscale kinetic transport: continuous-spectrum equations and coupled wave-particle iteration
Chang Liu, Kun Xu
The wave-particle decomposition is presented as a framework for multiscale kinetic transport, comprising a theory and an algorithm. Along the characteristics of the kinetic equatio…
Unified Gas-Kinetic Wave-Particle Method for Multiscale Simulation of Vlasov-Poisson-Fokker-Planck System
Zhigang Pu, Chang Liu, Yixiao Wang +1
A unified gas-kinetic wave--particle method with Fokker--Planck collisions (UGKWP-FP) is developed for the Vlasov--Poisson--Fokker--Planck system. The collision operator is modeled…
Wave-Particle Decomposition for Kinetic Equations I: Theory and Numerics
Chang Liu, Kun Xu
This paper presents a wave-particle decomposition (WPD) for kinetic relaxation equations, formulated around a local evolution timescale and its associated kinetic horizon. By lever…
Unified gas-kinetic wave-particle method for frequency-dependent radiation transport equation
Xiaojian Yang, Yajun Zhu, Chang Liu +1
The multi-frequency radiation transport equation (RTE) system models the photon transport and the energy exchange process between the background material and different frequency ph…
Gas-Kinetic Scheme for Partially Ionized Plasma in Hydrodynamic Regime
Zhigang Pu, Chang Liu, Kun Xu
Most plasmas are only partially ionized. To better understand the dynamics of these plasmas, the behaviors of a mixture of neutral species and plasma in ideal magnetohydrodynamic s…
A unified gas-kinetic particle method for frequency-dependent radiative transfer equations with isotropic scattering process on unstructured mesh
Yuan Hu, Chang Liu
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. T…
An implicit unified gas-kinetic wave-particle method for radiative transport process
Chang Liu, Weiming Li, Peng Song +1
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…
Unified gas-kinetic wave-particle methods VI: Disperse dilute gas-particle multiphase flow
Xiaojian Yang, Chang Liu, Xing Ji +2
In this paper, a unified gas-kinetic wave-particle scheme (UGKWP) for the disperse dilute gas-particle multiphase flow is proposed. The gas phase is always in the hydrodynamic regi…
General Implicit Iterative Method for Unified Gas-kinetic Scheme
Xiaocong Xu, Yajun Zhu, Chang Liu +1
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…
Unified gas-kinetic wave-particle methods V: diatomic molecular flow
Xiaocong Xu, Yipei Chen, Chang Liu +2
In this paper, the unified gas-kinetic wave-particle (UGKWP) method is further developed for diatomic gas with the energy exchange between translational and rotational modes for fl…
Unified Gas-kinetic Wave-Particle Method IV: Multi-species Gas Mixture and Plasma Transport
Chang Liu, Kun Xu
In this paper, we extend the unified gas-kinetic wave-particle (UGKWP) method to the multi-species gas mixture and multiscale plasma transport. The construction of the scheme is ba…
A Unified Gas-kinetic Scheme for Micro Flow Simulation Based on Linearized Kinetic Equation
Chang Liu, Kun Xu
The flow regime of micro flow varies from collisionless regime to hydrodynamic regime according to the Knudsen number. On the kinetic scale, the dynamics of micro flow can be descr…
Unified Gas-kinetic Wave-Particle Methods III: Multiscale Photon Transport
Weiming Li, Chang Liu, Yajun Zhu +2
In this paper, we extend the unified gas-kinetic wave-particle (UGKWP) method to the multiscale photon transport. In this method, the photon free streaming and scattering processes…
Unified Gas-kinetic Wave-Particle Methods II: Multiscale Simulation on Unstructured Mesh
Yajun Zhu, Chang Liu, Chengwen Zhong +1
In this paper, we present a unified gas-kinetic wave-particle (UGKWP) method on unstructured mesh for multiscale simulation of continuum and rarefied flow. Inheriting from the mult…
Unified Gas-kinetic Wave-Particle methods I: Continuum and Rarefied Gas Flow
Chang Liu, Yajun Zhu, Kun Xu
The unified gas-kinetic scheme (UGKS) provides a framework for simulating multiscale transport with the updates of both gas distribution function and macroscopic flow variables on…
A Unified Gas-kinetic Particle Method for Multiscale Photon Transport
Weiming Li, Chang Liu, Yajun Zhu +2
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 f…
A velocity-space adaptive unified gas kinetic scheme for continuum and rarefied flows
Tianbai Xiao, Kun Xu, Qingdong Cai
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 distrib…
A Unified Gas-kinetic Scheme for Continuum and Rarefied Flows VI: Dilute Disperse Gas-Particle Multiphase System
Chang Liu, Zhao Wang, Kun Xu
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 physi…
Cell Size Effect on Computational Fluid Dynamics: The Limitation Principle for Flow Simulation
Chang Liu, Kun Xu, Guangzhao Zhou
For theoretical gas dynamics, the flow regimes are classified according to the Knudsen number. For computational fluid dynamics (CFD), the numerical flow field is the projection of…
On the apparent permeability of porous media in rarefied gas flows
Lei Wu, M. T. Ho, Lefki Germanou +4
The apparent gas permeability of the porous medium is an important parameter in the prediction of unconventional gas production, which was first investigated systematically by Klin…
A comment on `An improved macroscale model for gas slip flow in porous media'
Lei Wu, Minh Tuan Ho, Lefki Germanou +4
In a recent paper by Lasseux, Valdés-Parada and Porter (J.~Fluid~Mech. \textbf{805} (2016) 118-146), it is found that the apparent gas permeability of the porous media is a nonline…
A Unified Gas Kinetic Scheme for Multi-scale and Multi-component Plasma Transport
Chang Liu, Kun Xu
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 so…