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A Cartesian grid method combined with a simplified gas kinetic scheme is presented for subsonic and supersonic viscous flow simulation on complex geometries. Under the Cartesian mesh, the computational grid points are classified into four…

Fluid Dynamics · Physics 2015-02-17 Songze Chen , Kun Xu , Zhihui Li

We present a numerical formulation for the solution of non-isothermal, compressible, Navier-Stokes equations with thermal fluctuations to describe mesoscale transport phenomena in multispecies fluid mixtures. The novelty of our numerical…

Computational fluid dynamics is a direct modeling of physical laws in a discretized space. The basic physical laws include the mass, momentum and energy conservations, physically consistent transport process, and similar domain of…

Fluid Dynamics · Physics 2021-07-15 Fengxiang Zhao , Xing Ji , Wei Shyy , Kun Xu

A new framework is introduced for constructing interpretable and truly reliable reduced models for multiscale problems in situations without scale separation. Hydrodynamic approximation to the kinetic equation is used as an example to…

Computational Physics · Physics 2019-10-31 Jiequn Han , Chao Ma , Zheng Ma , Weinan E

The stable operation of gas networks is an important optimization target. While for this task commonly finite volume methods are used, we introduce a new finite difference approach. With a summation by part formulation for the spatial…

Numerical Analysis · Mathematics 2021-08-31 Sonja Hossbach , Mathias Lemke , Julius Reiss

Existing Unbiased Scene Graph Generation (USGG) methods only focus on addressing the predicate-level imbalance that high-frequency classes dominate predictions of rare ones, while overlooking the concept-level imbalance. Actually, even if…

Computer Vision and Pattern Recognition · Computer Science 2024-07-17 Xinyu Lyu , Lianli Gao , Junlin Xie , Pengpeng Zeng , Yulu Tian , Jie Shao , Heng Tao Shen

The modeling and simulation of multiphase fluid flow receive significant attention in reservoir engineering. Many time discretization schemes for multiphase flow equations are either explicit or semi-implicit, relying on the decoupling…

Computational Physics · Physics 2025-06-06 Shuai Lu

Robust and accurate fully implicit finite-volume schemes applied to Darcy-scale multiphase flow and transport in porous media are highly desirable. Recently, a smooth approximation of the saturation-dependent flux coefficients based on…

Numerical Analysis · Mathematics 2019-09-17 Francois P. Hamon , Bradley T. Mallison

The multi-scale flow mechanism is crucial for force and heat loaded on near-space and reentry vehicles, the control of spacecraft by thrusters, the propelling and cooling of MEMS, etc. Since the continuum flow and rarefied flow often exist…

Computational Physics · Physics 2021-07-28 Sirui Yang , Sha Liu , Chengwen Zhong , Junzhe Cao , Congshan Zhuo

Oscillatory rarefied gas flows are frequently encountered in MEMS, and their efficient numerical simulation remains a major challenge due to the time dependent nature of the problem and the high dimensionality of the Boltzmann kinetic…

Computational Physics · Physics 2026-01-27 Pengshuo Li , Lei Wu

The boundary layer represents a fundamental structure in fluid dynamics, where accurate boundary discretization significantly enhances computational efficiency. This paper presents a third-order boundary discretization for compact…

Numerical Analysis · Mathematics 2025-03-07 Jiawang Zhang , Xing Ji , Kun Xu

Energy-sharing UAV-UGV systems extend the endurance of Uncrewed Aerial Vehicles (UAVs) by leveraging Uncrewed Ground Vehicles (UGVs) as mobile charging stations, enabling persistent autonomy in infrastructure-sparse environments. Trajectory…

Optimization and Control · Mathematics 2026-03-31 Minsen Yuan , Amanuel Adane , James Humann , Yue Yu

In this paper, the compact gas-kinetic scheme for compressible flow is extended to hybrid unstructured mesh. Based on both cell-averaged flow variables and their gradients updated from time accurate gas evolution model at cell interfaces, a…

Numerical Analysis · Mathematics 2021-12-22 Xing Ji , Wei Shyy , Kun Xu

This paper presents a kinetic model for the coupled evolution of radiation, electrons, and ions in a radiation plasma system. The model is solved using two methods. The gas-kinetic scheme (GKS) for electron and ion hydrodynamics and the…

Computational Physics · Physics 2025-01-10 Mingyu Quan , Xiaojian Yang , Yufeng Wei , Kun Xu

The low-variance direct simulation Monte Carlo (LVDSMC) is a powerful method to simulate low-speed rarefied gas flows. However, in the near-continuum flow regime, due to limitations on the time step and spatial cell size, it takes plenty of…

Fluid Dynamics · Physics 2022-10-18 Liyan Luo , Qi Li , Lei Wu

This paper introduces a memory-reduction third-order compact gas-kinetic scheme (CGKS) for solving compressible Euler and Navier-Stokes equations on 3D unstructured meshes. The scheme utilizes a time-evolution gas distribution function to…

Numerical Analysis · Mathematics 2024-08-21 Hongyu Liu , Xing Ji , Yunpeng Mao , Zhe Qian , 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

In this paper, a multiscale boundary condition for the discrete unified gas kinetic scheme (DUGKS) is developed for gas flows in all flow regimes. Based on the discrete Maxwell boundary condition (DMBC), this study addresses the limitations…

Fluid Dynamics · Physics 2025-10-28 Ziyang Xin , Yue Zhang , Chuang Zhang , Zhaoli Guo

We propose IMEX HDG-DG schemes for planar and spherical shallow water systems. Of interest is subcritical flow, where the speed of the gravity wave is faster than that of nonlinear advection. In order to simulate these flows efficiently, we…

Computational Engineering, Finance, and Science · Computer Science 2017-11-09 Shinhoo Kang , Francis X. Giraldo , Tan Bui-Thanh

In many power systems, particularly those isolated from larger intercontinental grids, operational dependence on natural gas becomes pivotal, especially during fluctuations or unavailability of renewables coupled with uncertain consumption…

Optimization and Control · Mathematics 2024-05-10 Criston Hyett , Laurent Pagnier , Jean Alisse , Igal Goldshtein , Lilah Saban , Robert Ferrando , Michael Chertkov