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The basic continuum model for polar fluids is deceptively simple. The free energy integral consists of four terms: The coupling of polarization to an external field, the electrostatic energy of the induced electric field interacting with…

Soft Condensed Matter · Physics 2021-12-22 Michiel Sprik

We model the dynamics of a closed quantum system brought out of mechanical equilibrium, undergoing a non-driven, spontaneous, thermodynamic transformation. In particular, we consider a quantum particle in a box with a moving and insulating…

Quantum Physics · Physics 2024-02-21 Sofia Sgroi , Mauro Paternostro

This study presents a novel pressure-based methodology for the efficient numerical solution of a four-equation two-phase diffuse interface model. The proposed methodology has the potential to simulate low-Mach flows with mass transfer. In…

Fluid Dynamics · Physics 2021-10-12 Andreas D. Demou , Nicoló Scapin , Marica Pelanti , Luca Brandt

We present a simple modification of the direct-forcing immersed boundary method (IBM) proposed by Uhlmann [J. Comput. Phys, 2005] in order to enable it to be applied to particulate flows with solid-to-fluid density ratios around unity. The…

Fluid Dynamics · Physics 2023-06-21 Manuel Garcia-Villalba , Blanca Fuentes , Jan Dusek , Manuel Moriche , Markus Uhlmann

Third-order approximate solutions for surface gravity waves in the finite water depth are studied in the context of potential flow theory. This solution provides explicit expressions for the surface elevation, free-surface velocity…

Fluid Dynamics · Physics 2021-09-15 Zhe Gao , Z. C Sun , S. X Liang

This work explores the capability of simulating complex fluid flows by directly solving the Boltzmann equation. Due to the high-dimensionality of the governing equation, the substantial computational cost of solving the Boltzmann equation…

Fluid Dynamics · Physics 2023-12-05 Tarik Dzanic , Luigi Martinelli

Einstein's field equations with cosmological constant are analysed for a static, spherically symmetric perfect fluid having constant density. Five new global solutions are described. One of these solutions has the Nariai solution joined on…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Christian G. Boehmer

In the astrophysics community it is common practice to model collisionless dust, entrained in a gas flow, as a pressureless fluid. However a pressureless fluid is fundamentally different from a collisionless fluid - the latter of which…

Earth and Planetary Astrophysics · Physics 2024-12-18 Elliot M. Lynch , Guillaume Laibe

We reduce Einstein's field equations for the interior of a uniformly rotating, axisymmetric perfect fluid to a system of six second order partial differential equations for the pressure p the energy density $\mu$ and four dependent…

General Relativity and Quantum Cosmology · Physics 2016-08-31 E. Kyriakopoulos

In this paper, a three-dimensional numerical solver is developed for suspensions of rigid and soft particles and droplets in viscoelastic and elastoviscoplastic (EVP) fluids. The presented algorithm is designed to allow for the first time…

We introduce a second-order numerical scheme for compressible atmospheric motions at small to planetary scales. The collocated finite volume method treats the advection of mass, momentum, and mass-weighted potential temperature in…

Numerical Analysis · Mathematics 2020-01-08 Tommaso Benacchio , Rupert Klein

We obtain an approximate global stationary and axisymmetric solution of Einstein's equations which can be considered as a simple star model: a self-gravitating perfect fluid ball with constant mass density rotating in rigid motion. Using…

General Relativity and Quantum Cosmology · Physics 2008-11-26 J. A. Cabezas , J. Martin-Martin , A. Molina , E. Ruiz

In this paper, the compressible quantum model with the given mass source and the external force of general form in three-dimensional whole space is considered. Based on the weighted $L^2$ method and $L^\infty$ estimates, the existence and…

Analysis of PDEs · Mathematics 2021-10-27 Xiaoyu Xi

Gravity currents are a ubiquitous density driven flow occurring in both the natural environment and in industry. They include: seafloor turbidity currents, primary vectors of sediment, nutrient and pollutant transport; cold fronts; and…

Fluid Dynamics · Physics 2025-02-28 Edward W. G. Skevington , Robert M. Dorrell

We present a well-balanced, second order, Godunov-type finite volume scheme for compressible Euler equations with gravity. By construction, the scheme admits a discrete stationary solution which is a second order accurate approximation to…

Numerical Analysis · Mathematics 2019-02-07 Deepak Varma , Praveen Chandrashekar

We develop, and implement in a Finite Volume environment, a density-based approach for the Euler equations written in conservative form using density, momentum, and total energy as variables. Under simplifying assumptions, these equations…

Numerical Analysis · Mathematics 2024-05-01 Nicola Clinco , Michele Girfoglio , Annalisa Quaini , Gianluigi Rozza

We consider anisotropic fluids with directional pressures $p_i = w_i \rho$ ($\rho$ is the density, $w_i = $const, $i = 1,2,3$) as sources of gravity in stationary cylindrically symmetric space-times. We describe a general way of obtaining…

General Relativity and Quantum Cosmology · Physics 2019-06-19 S. V. Bolokhov , K. A. Bronnikov , M. V. Skvortsova

We consider the Dirichlet problem for a compressible two-fluid model in three dimensions, and obtain the global existence of weak solution with large initial data and independent adiabatic constants \Gamma,\gamma>=9/5. The pressure…

Analysis of PDEs · Mathematics 2021-07-27 Huanyao Wen

We present an algorithm to generalize a plethora of well-known solutions to Einstein field equations describing spherically symmetric relativistic fluid spheres by relaxing the pressure isotropy condition on the system. By suitably fixing…

General Physics · Physics 2018-02-14 S. Thirukkanesh , F. C. Ragel , Ranjan Sharma , Shyam Das

We propose a new reduced model for gravity-driven free-surface flows of shallow elastic fluids. It is obtained by an asymptotic expansion of the upper-convected Maxwell model for elastic fluids. The viscosity is assumed small (of order…

Numerical Analysis · Mathematics 2013-06-13 François Bouchut , Sébastien Boyaval