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Two-dimensional free-surface flow over localised topography is examined with the emphasis on the stability of hydraulic-fall solutions. A Gaussian topography profile is assumed with a positive or negative amplitude modelling a bump or a…

Fluid Dynamics · Physics 2024-03-12 Jack S. Keeler , Mark G. Blyth

We propose an extension to recently developed Relativistic Lattice Boltzmann solvers (RLBM), which allows the simulation of flows close to the free streaming limit. Following previous works [Phys. Rev. C 98 (2018) 035201], we use product…

Modern simulation codes for general relativistic ideal magnetohydrodynamics are all facing a long standing technical problem given by the need to recover fundamental variables from those variables that are evolved in time. In the…

General Relativity and Quantum Cosmology · Physics 2021-01-26 Wolfgang Kastaun , Jay Vijay Kalinani , Riccardo Ciolfi

We introduce a notion of stability for non-autonomous Hamiltonian flows on two-dimensional annular surfaces. This notion of stability is designed to capture the sustained twisting of particle trajectories. The main Theorem is applied to…

Analysis of PDEs · Mathematics 2024-08-30 Theodore D. Drivas , Tarek M. Elgindi , In-Jee Jeong

While exact and approximate Riemann solvers are widely used, they exhibit two fundamental limitations: 1) Fail to represent continuous entropy transport processes, resulting in thermodynamic incompatibility that limits their applicability…

Numerical Analysis · Mathematics 2026-01-26 Zhixin Huo

The magnetohydrodynamic equations system for heavy fluid over an arbitrary surface in shallow water approximation is studied in the present paper. It is shown that simple wave solutions exist only for underlying surfaces that are slopes of…

Fluid Dynamics · Physics 2015-05-27 Kirill Karelsky , Arakel Petrosyan , Stepan Tarasevich

Numerical methods for the Euler equations with a singular source are discussed in this paper. The stationary discontinuity induced by the singular source and its coupling with the convection of fluid presents challenges to numerical…

Numerical Analysis · Mathematics 2022-03-14 Changsheng Yu , Tiegang Liu , Chengliang Feng

A collection of arbitrarily-shaped solid objects, each moving at a constant speed, can be used to mix or stir ideal fluid, and can give rise to interesting flow patterns. Assuming these systems of fluid stirrers are two-dimensional, the…

Complex Variables · Mathematics 2017-01-03 Mohamed M. S. Nasser , Christopher C. Green

We consider the two dimensional unsteady Prandtl system. For a special class of outer Euler flows and solutions of the Prandtl system, the trace of the tangential derivative of the tangential velocity along the transversal axis solves a…

Analysis of PDEs · Mathematics 2022-04-08 Charles Collot , Tej-Eddine Ghoul , Slim Ibrahim , Nader Masmoudi

The classical system of shallow-water (Saint--Venant) equations describes long surface waves in an inviscid incompressible fluid of a variable depth. Although shock waves are expected in this quasilinear hyperbolic system for a wide class…

Analysis of PDEs · Mathematics 2016-03-16 Sergey N. Alexeenko , Marina V. Dontsova , Dmitry E. Pelinovsky

We introduce a new notion of viscosity solutions for a class of very singular nonlinear parabolic problems of non-divergence form in a periodic domain of arbitrary dimension, whose diffusion on flat parts with zero slope is so strong that…

Analysis of PDEs · Mathematics 2013-02-05 Mi-Ho Giga , Yoshikazu Giga , Norbert Pozar

Normalizing flows have shown great promise for modelling flexible probability distributions in a computationally tractable way. However, whilst data is often naturally described on Riemannian manifolds such as spheres, torii, and hyperbolic…

Machine Learning · Statistics 2020-12-10 Emile Mathieu , Maximilian Nickel

Porosity-based models are a viable alternative to classical two-dimensional (2-d) Shallow water Equations (SWE) when the interaction of shallow flows with obstacles is modelled. The exact solution of the Single Porosity (SP) Riemann…

Fluid Dynamics · Physics 2023-07-18 Giada Varra , Renata Della Morte , Luigi Cimorelli , Luca Cozzolino

A new approach to the solution of quasilinear nonelliptic first-order systems of inhomogeneous PDEs in many dimensions is presented. It is based on a version of the conditional symmetry and Riemann invariant methods. We discuss in detail…

Mathematical Physics · Physics 2015-05-19 A. Michel Grundland , Benoit Huard

The observation of fluid-like behavior in nucleus-nucleus, proton-nucleus and high-multiplicity proton-proton collisions motivates systematic studies of how different measurements approach their fluid-dynamic limit. We have developed…

High Energy Physics - Phenomenology · Physics 2020-11-11 Aleksi Kurkela , Seyed Farid Taghavi , Urs Achim Wiedemann , Bin Wu

Relativistic hydrodynamics of an isentropic fluid in a gravitational field is considered as the particular example from the family of Lagrangian hydrodynamic-type systems which possess an infinite set of integrals of motion due to the…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Victor P. Ruban

In this paper, we aim to address several important issues about the recently developed lattice Boltzmann (LB) model for relativistic hydrodynamics [M. Mendoza et al., Phys. Rev. Lett. 105, 014502 (2010); Phys. Rev. D 82, 105008 (2010)].…

Computational Physics · Physics 2012-11-15 Q. Li , K. H. Luo , X. J. Li

We study the problem of coupling Einstein's equations to a relativistic and physically well-motivated version of the Navier-Stokes equations. Under a natural evolution condition for the vorticity, we prove existence and uniqueness in a…

Mathematical Physics · Physics 2016-04-08 Magdalena Czubak , Marcelo M. Disconzi

The characteristic decomposition for GRMHD is not known in a form useful for current numerical simulations. This prevents us from using the most accurate known computational methods, such as full-wave Riemann solvers. In this paper, we…

General Relativity and Quantum Cosmology · Physics 2025-11-19 Saul A. Teukolsky

We use a simple model consisting of energy-momentum tensor conservation and a Maxwell-Cattaneo equation for its viscous part to study nonlinear phenomena in a real relativistic fluid. We focus on new types of behavior without…

General Relativity and Quantum Cosmology · Physics 2021-03-31 Esteban Calzetta