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We present a positivity-preserving method for multi-resolution simulations of compressible flows involving extreme conditions such as near vacuum and strong discontinuities. The novelty of this work is due to two aspects. First we extend…

Computational Physics · Physics 2018-07-19 Shuccheng Pan , Xiangyu Hu , Nikolaus Adams

In this work we use tempered fractional advection-diffusion equations to model the dispersive transport in disordered materials. A numerical method is derived to approximate the solution of such differential models and we prove that it is…

Numerical Analysis · Mathematics 2018-11-06 Maria Luísa Morgado , Luís Filipe Morgado

This paper presents a space-time interface-fitted finite element method for solving a parabolic advection-diffusion problem with a nonstationary interface. The jumping diffusion coefficient gives rise to the discontinuity of the solution…

Numerical Analysis · Mathematics 2025-01-13 Quang Huy Nguyen , Van Chien Le , Phuong Cuc Hoang , Thi Thanh Mai Ta

In this paper, two approaches for modeling three-component fluid flows using diffusive interface method are discussed. Thermodynamic consistency of the proposed models is preserved when using an energetic variational framework to derive the…

Analysis of PDEs · Mathematics 2018-10-12 Arkadz Kirshtein , James Brannick , Chun Liu

The charging of insulating samples degrades the quality and complicates the interpretation of images in scanning electron microscopy and is important in other applications, such as particle detectors. In this paper we analyze this…

Classical Physics · Physics 2020-06-19 Behrouz Raftari , Neil Budko , Kees Vuik

Over three decades ago the advection-diffusion equation for a steady fluid velocity field was homogenized, leading to a Stieltjes integral representation for the effective diffusivity, which is given in terms of a spectral measure of a…

Fluid Dynamics · Physics 2024-04-30 N. B. Murphy , D. Hallman , E. Cherkaev , J. Xin , K. M. Golden

It is widely assumed that thermionic current flow through a plasma is limited by a "space-charge limited" (SCL) cathode sheath that consumes the hot cathode's negative bias and accelerates upstream ions into the cathode. Here, we formulate…

Plasma Physics · Physics 2018-04-25 Michael D. Campanell

Immersed boundary methods for computing confined fluid and plasma flows in complex geometries are reviewed. The mathematical principle of the volume penalization technique is described and simple examples for imposing Dirichlet and Neumann…

Plasma Physics · Physics 2015-10-07 Kai Schneider

Active particles often swim in confined environments. The transport mechanisms, especially the global one as reflected by the Taylor dispersion model, are of great practical interest to various applications. For active dispersion process in…

Fluid Dynamics · Physics 2023-06-22 Weiquan Jiang , Guoqian Chen

A fundamental problem in plasma physics, space science, and astrophysics is the transport of energetic particles interacting with stochastic magnetic fields. In particular the motion of particles across a large scale magnetic field is…

Space Physics · Physics 2015-08-26 Andreas Shalchi

Many practical samplers rely on time-dependent drifts -- often induced by annealing or tempering schedules -- to improve exploration and stability. This motivates a unified non-asymptotic analysis of the corresponding Langevin diffusions…

Numerical Analysis · Mathematics 2026-05-12 Andreas Habring , Martin Zach

We investigate the response of a relativistic plasma to electromagnetic fields in the framework of the Boltzmann equation incorporating a collision term in the relaxation rate approximation selected in a form assuring current conservation.…

Plasma Physics · Physics 2022-01-05 Martin Formanek , Christopher Grayson , Johann Rafelski , Berndt Müller

Recent results on the fluid dynamic limits of the Boltzmann equation based on the DiPerna-Lions theory of renormalized solutions are reviewed in this paper, with an emphasis on regimes where the velocity field behaves to leading order like…

Analysis of PDEs · Mathematics 2012-07-26 François Golse

In this paper, we study the asymptotic estimate of solution for a mixed-order time-fractional diffusion equation in a bounded domain subject to the homogeneous Dirichlet boundary condition. Firstly, the unique existence and regularity…

Analysis of PDEs · Mathematics 2021-08-26 Zhiyuan Li , Xinchi Huang , Masahiro Yamamoto

This paper establishes the convergence of a time-steeping scheme for time fractional diffusion problems with nonsmooth data. We first analyze the regularity of the model problem with nonsmooth data, and then prove that the time-steeping…

Numerical Analysis · Mathematics 2018-04-30 Binjie Li , Hao Luo , Xiaoping Xie

In this work, we develop an accelerated sharp-interface method based on (Hu et al., JCP, 2006) and (Luo et al., JCP, 2015) for multiphase flows simulations. Traditional multiphase simulation methods use the minimum time step of all fluids…

Computational Physics · Physics 2019-05-13 Tian Long , Jinsheng Cai , Shucheng Pan

The diffusion model has shown success in generating high-quality and diverse solutions to trajectory optimization problems. However, diffusion models with neural networks inevitably make prediction errors, which leads to constraint…

Machine Learning · Computer Science 2024-06-04 Anjian Li , Zihan Ding , Adji Bousso Dieng , Ryne Beeson

This work presents a comparative study of the best models available to describe granular fluids in order to investigate the extent to which it makes sense to speak about a liquid-gas transition in a system of particles that present no…

Soft Condensed Matter · Physics 2024-09-02 O. Coquand

Two-fluid plasma flow equations describe the flow of ions and electrons with different densities, velocities, and pressures. We consider the ideal plasma flow i.e. we ignore viscous, resistive, and collision effects. The resulting system of…

Numerical Analysis · Mathematics 2024-09-25 Jaya Agnihotri , Deepak Bhoriya , Harish Kumar , Praveen Chandrashekhar , Dinshaw S. Balsara

A new phase field model is introduced, which can be viewed as nontrivial generalisation of what is known as the Caginalp model. It involves in particular nonlinear diffusion terms. By formal asymptotic analysis, it is shown that in the…

Analysis of PDEs · Mathematics 2012-01-18 Sylvie Benzoni-Gavage , Laurent Chupin , Didier Jamet , Julien Vovelle