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200 papers

A new concept of semi-compressible fluids is introduced for slightly compressible visco-elastic fluids (typically rather liquids than gasses) where mass density variations are negligible in some sense, while being directly controlled by…

Analysis of PDEs · Mathematics 2020-04-17 Tomáš Roubíček

Gravitational waves are being shown to derive directly from Newtonian dynamics for a continuous mass distribution, e g compressible fluids or equivalent. It is shown that the equations governing a continuous mass distribution, i e the…

General Physics · Physics 2024-05-20 Peter Vadasz

We show that a reformulation of the governing equations for incompressible multi-phase flow in the volume of fluid setting leads to a well defined energy rate. Weak nonlinear inflow-outflow and solid wall boundary conditions complement the…

Analysis of PDEs · Mathematics 2024-12-31 Jan Nordström , Arnaud. G. Malan

We investigate the dependency of the inflow-wind structure of the hot accretion flow on the kinematic viscosity coefficient. In this regard, we propose a model for the kinematic viscosity coefficient to mimic the behavior of the…

High Energy Astrophysical Phenomena · Physics 2021-09-15 Fatemeh Zahra Zeraatgari , Liquan Mei , Amin Mosallanezhad

The classical theorems of inviscid stability have been extended for compressible flows past compliant surfaces. We consider normal modes imposed on a plane parallel compressible flow past compliant walls modelled as spring-backed plates and…

Fluid Dynamics · Physics 2024-01-29 Mandeep Deka , Gaurav Tomar , Viswanathan Kumaran

We systematically derived hydrodynamic equations and transport coefficients for a class of multi-speed lattice Boltzmann models in D dimensions, using the multi-scale technique. The constitutive relation of physical fluid is recovered by a…

comp-gas · Physics 2008-02-03 Yu Chen , Hirotada Ohashi , Mamoru Akiyama

We present a new, approximate method for modelling the acceleration and collimation of relativistic jets in the presence of gravity. This method is self-similar throughout the computational domain where gravitational effects are negligible…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Peter Polko , David L. Meier , Sera Markoff

In this paper we develop an existence theory for small amplitude, steady, two-dimensional water waves in the presence of wind in the air above. The presence of the wind is modeled by a Kelvin--Helmholtz type discontinuity across the…

Analysis of PDEs · Mathematics 2012-11-15 Samuel Walsh , Oliver Bühler , Jalal Shatah

We develop an analytic, steady-state model for the gas environment in quiescent galactic nuclei. We assume that the mass is constantly supplied by a spherically symmetric distribution of wind emitting stars, and that gravity is solely due…

Astrophysics of Galaxies · Physics 2018-07-18 Almog Yalinewich , Re'em Sari , Aleksey Generozov , Nicholas Chamberlain Stone , Brian David Metzger

The Hamiltonian dynamics of a compressible inviscid fluid is formulated as a gauge theory. The idea of gauge equivalence is exploited to unify the study of apparantly distinct physical problems and solutions of new models can be generated…

High Energy Physics - Theory · Physics 2007-05-23 Subir Ghosh

In this paper we establish the incompressible limit for the compressible free-boundary Euler equations with surface tension in the case of a liquid. Compared to the case without surface tension treated recently, the presence of surface…

Analysis of PDEs · Mathematics 2020-05-14 Marcelo M. Disconzi , Chenyun Luo

We develop the analysis of finite element approximations of implicit power-law-like models for viscous incompressible fluids. The Cauchy stress and the symmetric part of the velocity gradient in the class of models under consideration are…

Numerical Analysis · Mathematics 2013-10-30 Lars Diening , Christian Kreuzer , Endre Süli

While compressible flow theory has relied on the perfect gas model as its workhorse for the past century, compressible dynamics in dense gases, solids and liquids have relied on many complex equations of state, yielding limited insight on…

Fluid Dynamics · Physics 2020-04-21 Matei Ioan Radulescu

We present the structure of a low angular momentum accretion flows around rotating compact objects incorporating relativistic corrections up to the leading post-Newtonian order. To begin with, we formulate the governing post-Newtonian…

High Energy Astrophysical Phenomena · Physics 2024-05-09 Elham Nazari , Samik Mitra , Shahram Abbassi , Santabrata Das

Slow flows of an ideal compressible fluid (gas) in the gravity field in the presence of two isentropic layers are considered, with a small difference of specific entropy between them. Assuming irrotational flows in each layer [that is ${\bf…

Atmospheric and Oceanic Physics · Physics 2010-12-30 V. P. Ruban

In this article we study the asymptotic behavior of incompressible, ideal, time-dependent two dimensional flow in the exterior of a single smooth obstacle when the size of the obstacle becomes very small. Our main purpose is to identify the…

Fluid Dynamics · Physics 2007-05-23 D. Iftimie , M. C. Lopes Filho , H. J. Nussenzveig Lopes

In this paper, the problem of compressible flow over a thin airfoil located near the ground is studied. A singular integral equation, also known as Possio equation, that relates the pressure jump along the airfoil to its downwash is…

Fluid Dynamics · Physics 2017-02-16 Mohamed Serry , Amjad Tuffaha

In this paper we develop two models for the steady states and evolution of two dimensional isothermal self gravitating and rotating incompressible gas which are based on the hydrodynamic equations for stratified fluid. The first model is…

Earth and Planetary Astrophysics · Physics 2015-04-14 Mayer Humi , Zilu Tian

Acoustic perturbations in a parallel relativistic flow of an inviscid fluid are considered. The general expression for the frequency of the sound waves in a uniformly (with zero shear) moving medium is derived. It is shown that relativity…

Astrophysics · Physics 2007-05-23 A. D. Rogava , V. I. Berezhiani , S. M. Mahajan

We consider a sequence of approximate solutions to the compressible Euler system admitting uniform energy bounds and/or satisfying the relevant field equations modulo an error vanishing in the asymptotic limit. We show that such a sequence…

Analysis of PDEs · Mathematics 2020-01-03 Eduard Feireisl , Martina Hofmanová