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We present approximate exterior and interior solutions of Einstein's equations which describe the gravitational field of a static deformed mass distribution. The deformation of the source is taken into account up to the first order in the…

General Relativity and Quantum Cosmology · Physics 2016-03-16 Medeu Abishev , Kuantay Boshkayev , Hernando Quevedo , Saken Toktarbay

The idea that spacetime points are to be identified by a fleet of clock--carrying particles can be traced to the earliest days of general relativity. Such a fleet of clocks can be described phenomenologically as a reference fluid. One…

General Relativity and Quantum Cosmology · Physics 2007-05-23 David Brown

A linear relationship between the Hubble expansion parameter and the time derivative of the scalar field is assumed in order to derive exact analytic cosmological solutions to Einstein's gravity with two fluids: a barotropic perfect fluid…

General Relativity and Quantum Cosmology · Physics 2009-09-29 Olga Arias , Tame Gonzalez , Israel Quiros

The concept of inverse energy cascades has played a central role in the development of turbulence theory, with applications in two-dimensional and quasi-two-dimensional flows. We examine the presence or absence of inverse energy cascades in…

Fluid Dynamics · Physics 2026-03-11 Alexandros Alexakis , Raffaele Marino , Pablo D. Mininni

We present the derivation of a new unidirectional model for We present the derivation of a new unidirectional model for unsteady mixed flows in non uniform closed water pipes. We introduce a local reference frame to take into account the…

Analysis of PDEs · Mathematics 2010-06-02 Christian Bourdarias , Mehmet Ersoy , Stéphane Gerbi

In this work, we introduce an iterative linearised finite element method for the solution of Bingham fluid flow problems. The proposed algorithm has the favourable property that a subsequence of the sequence of iterates generated converges…

Numerical Analysis · Mathematics 2021-09-14 Pascal Heid , Endre Süli

Multidimensional cosmological model describing the evolution of a fluid with shear and bulk viscosity in $n$ Ricci-flat spaces is investigated. The barotropic equation of state for the density and the pressure in each space is assumed. The…

General Relativity and Quantum Cosmology · Physics 2010-04-30 V. R. Gavrilov , V. N. Melnikov , Roland Triay

Humans have a strong intuitive understanding of physical processes such as fluid falling by just a glimpse of such a scene picture, i.e., quickly derived from our immersive visual experiences in memory. This work achieves such a…

Computer Vision and Pattern Recognition · Computer Science 2023-04-11 Jinxian Liu , Ye Chen , Bingbing Ni , Jiyao Mao , Zhenbo Yu

We consider the inverse mean curvature flow in Robertson-Walker spacetimes that satisfy the Einstein equations and have a big crunch singularity and prove that under natural conditions the rescaled inverse mean curvature flow provides a…

General Relativity and Quantum Cosmology · Physics 2007-05-23 Claus Gerhardt

The dynamics of sound in a fluid is intrinsically nonlinear. We derive the consequences of this fact for the analogue gravitational field experienced by sound waves, by first describing generally how the nonlinearity of the equation for…

General Relativity and Quantum Cosmology · Physics 2022-12-01 Satadal Datta , Uwe R. Fischer

A kind of problems of radially symmetric transient fluid flow in a medium with a geometry similar to a hollow-disk can be addressed using the finite Hankel transform. However, the inverse Hankel transform [G. Cinelli, Int. J. Engng. Sci.,…

Analysis of PDEs · Mathematics 2019-12-10 Luis X. Vivas-Cruz , Jorge Adrián Perera-Burgos , Alfredo González-Calderón

In this note we consider general formulation of Euler's equations for an inviscid incompressible homogeneous fluid with an oscillating body force. Our aim is to derive the averaged equations for these flows with the help of two-timing…

Fluid Dynamics · Physics 2016-08-24 V. A. Vladimirov , N. Peake

In the finite element analysis with fast decoupled time integration scheme for viscoelastic fluid (the Leonov model) flow, we investigate strong nonlinear behavior in 2D creeping contraction flow. The algorithm is applicable in the whole…

Fluid Dynamics · Physics 2011-11-02 Youngdon Kwon

Einstein's field equations for spatially self-similar locally rotationally symmetric perfect fluid models are investigated. The field equations are rewritten as a first order system of autonomous ordinary differential equations.…

General Relativity and Quantum Cosmology · Physics 2009-10-28 Ulf Nilsson , Claes Uggla

We consider a one dimensional transport model with nonlocal velocity given by the Hilbert transform and develop a global well-posedness theory of probability measure solutions. Both the viscous and non-viscous cases are analyzed. Both in…

Analysis of PDEs · Mathematics 2011-11-01 J. A. Carrillo , L. C. F. Ferreira , J. C. Precioso

This study presents a conditional flow matching framework for solving physics-constrained Bayesian inverse problems. In this setting, samples from the joint distribution of inferred variables and measurements are assumed available, while…

A turbulent flow is maintained by an external supply of kinetic energy, which is eventually dissipated into heat at steep velocity gradients. The scale at which energy is supplied greatly differs from the scale at which energy is…

Fluid Dynamics · Physics 2015-06-30 Haitao Xu , Alain Pumir , Eberhard Bodenschatz

We consider an isothermal compressible fluid evolving on a cosmological background which may be either expanding or contracting toward the future. The Euler equations governing such a flow consist of two nonlinear hyperbolic balance laws…

Analysis of PDEs · Mathematics 2022-10-12 Yangyang Cao , Mohammad A. Ghazizadeh , Philippe G. LeFloch

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

We consider the statistical inverse problem of estimating a background fluid flow field $\mathbf{v}$ from the partial, noisy observations of the concentration $\theta$ of a substance passively advected by the fluid, so that $\theta$ is…

Statistics Theory · Mathematics 2019-09-16 Jeff Borggaard , Nathan E. Glatt-Holtz , Justin A. Krometis