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The present work focuses on the numerical approximation of the weak solutions of the shallow water model over a non-flat topography. In particular, we pay close attention to steady solutions with nonzero velocity. The goal of this work is…

Numerical Analysis · Mathematics 2025-01-08 Christophe Berthon , Victor Michel-Dansac

Physical systems with complex unsteady dynamics, such as fluid flows, are often poorly represented by a single mean solution. For many practical applications, it is crucial to access the full distribution of possible states, from which…

Computational Physics · Physics 2025-04-07 Mario Lino , Tobias Pfaff , Nils Thuerey

We quantify if the chemical abundance gradients given by a dynamical model of core collapse including time-dependent changes in density and temperature differ greatly from abundances derived from static models, where the density and…

Astrophysics of Galaxies · Physics 2018-07-18 O. Sipilä , P. Caselli

An algorithm for simulating self-gravitating cosmological astrophysical fluids is presented. The advantages include a large dynamic range, parallelizability, high resolution per grid element and fast execution speed. The code is based on a…

Astrophysics · Physics 2009-10-30 Ue-Li Pen

High-fidelity, high-resolution numerical simulations are crucial for studying complex multiscale phenomena in fluid dynamics, such as turbulent flows and ocean waves. However, direct numerical simulations with high-resolution solvers are…

Numerical Analysis · Mathematics 2025-04-14 Wuzhe Xu , Yulong Lu , Lian Shen , Anqing Xuan , Ali Barzegari

We describe a new algorithm to solve the time dependent, frequency integrated radiation transport (RT) equation implicitly, which is coupled to an explicit solver for equations of magnetohydrodynamics (MHD) using {\sf Athena++}. The…

Instrumentation and Methods for Astrophysics · Physics 2021-04-07 Yan-Fei Jiang

While diffusion models can successfully generate data and make predictions, they are predominantly designed for static images. We propose an approach for efficiently training diffusion models for probabilistic spatiotemporal forecasting,…

Machine Learning · Computer Science 2023-10-12 Salva Rühling Cachay , Bo Zhao , Hailey Joren , Rose Yu

We present a scheme to solve the nonlinear multigroup radiation diffusion (MGD) equations. The method is incorporated into a massively parallel, multidimensional, Eulerian radiation-hydrodynamic code with adaptive mesh refinement (AMR). The…

Astrophysics · Physics 2008-11-26 A. I. Shestakov , S. S. R. Offner

We present a dual-resolution molecular dynamics (MD) simulation of liquid water employing a recently introduced Adaptive Resolution Scheme (AdResS). The spatially adaptive molecular resolution procedure allows for changing from a…

Soft Condensed Matter · Physics 2011-11-10 Silvina Matysiak , Cecilia Clementi , Matej Praprotnik , Kurt Kremer , Luigi Delle Site

Hydrodynamic interactions in a suspension of spherical particles confined between two parallel planar walls are studied under creeping-flow conditions. The many-particle friction matrix in this system is evaluated using our novel numerical…

Fluid Dynamics · Physics 2009-11-11 S. Bhattacharya , J. Blawzdziewicz , E. Wajnryb

We present a novel approach to define the filter and relax steps in the evolve-filter-relax (EFR) framework for simulating turbulent flows. The EFR main advantages are its ease of implementation and computational efficiency. However, as it…

A direct numerical solution of the radiative transfer equation or any kinetic equation is typically expensive, since the radiative intensity depends on time, space and direction. An expansion in the direction variables yields an equivalent…

Mathematical Physics · Physics 2023-10-10 Benjamin Seibold , Martin Frank

A reduced-order model algorithm, based on approximations of Lax pairs, is proposed to solve nonlinear evolution partial differential equations. Contrary to other reduced-order methods, like Proper Orthogonal Decomposition, the space where…

Numerical Analysis · Mathematics 2012-11-20 Jean-Frédéric Gerbeau , Damiano Lombardi

Ordinary differential equations (ODEs) are widely used to describe dynamical systems in science, but identifying parameters that explain experimental measurements is challenging. In particular, although ODEs are differentiable and would…

Machine Learning · Computer Science 2024-07-22 Jonas Beck , Nathanael Bosch , Michael Deistler , Kyra L. Kadhim , Jakob H. Macke , Philipp Hennig , Philipp Berens

We consider the hydrodynamic behavior of some conservative particle systems with degenerate jump rates without exclusive constraints. More precisely, we study the particle systems without restrictions on the total number of particles per…

Probability · Mathematics 2017-05-01 Makiko Sasada

Many complex systems exhibit hydrodynamic (or macroscopic) behavior at large scales characterized by few variables such as the particle number density, temperature and pressure obeying a set of hydrodynamic (or macroscopic) equations. Does…

Disordered Systems and Neural Networks · Physics 2013-01-29 Chushun Tian

The equation governing the streaming of a quantity down its gradient superficially looks similar to the simple constant velocity advection equation. In fact, it is the same as an advection equation if there are no local extrema in the…

High Energy Astrophysical Phenomena · Physics 2015-03-13 Prateek Sharma , Phillip Colella , Daniel F. Martin

The Gradient Scheme framework provides a unified analysis setting for many different families of numerical methods for diffusion equations. We show in this paper that the Gradient Scheme framework can be adapted to elasticity equations, and…

Numerical Analysis · Mathematics 2014-02-18 Jerome Droniou , Bishnu P. Lamichhane

We present two promising applications of training machine learning models inside a differentiable astrophysical (magneto)hydrodynamics simulator. First, we address the problem of slow convergence in hydrodynamical simulations of wind-blown…

Instrumentation and Methods for Astrophysics · Physics 2025-12-09 Leonard Storcks , Tobias Buck

Radiation hydrodynamics simulations based on the one-fluid two-temperature model may violate the law of energy conservation because the governing equations are expressed in a nonconservative formulation. Here, we maintain the important…

Plasma Physics · Physics 2018-03-09 Takashi Shiroto , Soshi Kawai , Naofumi Ohnishi