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In this two-parts paper, we present a systematic procedure to extend the known Hamiltonian model of ideal inviscid fluid flow on Riemannian manifolds in terms of Lie-Poisson structures to a port-Hamiltonian model in terms of Stokes-Dirac…

Differential Geometry · Mathematics 2021-05-05 Ramy Rashad , Federico Califano , Frederic P. Schuller , Stefano Stramigioli

We construct a generally-covariant formulation of non-equilibrium thermodynamics in General Relativity. We find covariant entropic forces arising from gradients of the entropy density, and a corresponding non-conservation of the energy…

General Relativity and Quantum Cosmology · Physics 2021-10-20 Llorenc Espinosa-Portales , Juan Garcia-Bellido

The general relativistic non--linear dynamics of a self--gravitating collisionless fluid with vanishing vorticity is studied in synchronous and comoving -- i.e. {\em Lagrangian} -- coordinates. Writing the equations in terms of the metric…

Astrophysics · Physics 2007-05-23 Sabino Matarrese

We develop a new formalism for the treatment of gravitational backreaction in the cosmological setting. The approach is inspired by projective techniques in non-equilibrium statistical mechanics. We employ group-averaging with respect to…

General Relativity and Quantum Cosmology · Physics 2009-11-06 Charis Anastopoulos

We generalize the kinetic theory of fluids, in which the description of fluids is based on the geodesic motion of particles, to spacetimes modeled by Finsler geometry. Our results show that Finsler spacetimes are a suitable background for…

General Relativity and Quantum Cosmology · Physics 2016-01-25 Manuel Hohmann

We use null spherical (observational) coordinates to describe a class of inhomogeneous cosmological models. The proposed cosmological construction is based on the observer past null cone. A known difficulty in using inhomogeneous models is…

General Relativity and Quantum Cosmology · Physics 2009-11-10 Mustapha Ishak

We suggest the Hamiltonian approach for fluid mechanics based on the dynamics, formulated in terms of Lagrangian variables. The construction of the canonical variables of the fluid sheds a light of the origin of Clebsh variables, introduced…

High Energy Physics - Theory · Physics 2007-05-23 I. Antoniou , G. P. Pronko

In this Letter we construct the noncommutative (NC) gravity model on the $\theta$-constant NC space-time. We start from the NC $SO(2,3)_\star$ gauge theory and use the enveloping algebra approach and the Seiberg-Witten map to construct the…

High Energy Physics - Theory · Physics 2017-08-02 Marija Dimitrijevic Ciric , Biljana Nikolic , Voja Radovanovic

We study the hydrodynamic-type system of differential equations modeling isothermal no-slip drift flux. Using the facts that the system is partially coupled and its subsystem reduces to the (1+1)-dimensional Klein--Gordon equation, we…

Analysis of PDEs · Mathematics 2020-06-23 Stanislav Opanasenko , Alexander Bihlo , Roman O. Popovych , Artur Sergyeyev

In the standard model of cosmology, the background evolution of the Universe can in general be adequately described by general relativity and a uniform and isotropic metric minimally coupled with a collection of perfect fluids. These fluids…

General Relativity and Quantum Cosmology · Physics 2022-07-19 R. P. L. Azevedo

We developed the spacetime-covariant Hamilton principle for barotropic flows of a perfect fluid in the external axial-vector potential conjugate to the helicity current. Such flows carry helicity, a chiral imbalance, controlled by the axial…

High Energy Physics - Theory · Physics 2024-04-01 P. B. Wiegmann

In this paper cosmological dynamics in Einstein-Gauss-Bonnet gravity with a perfect fluid source in arbitrary dimension is studied. A systematic analysis is performed for the case that the theory does not admit maximally symmetric…

General Relativity and Quantum Cosmology · Physics 2018-03-15 Fabrizio Canfora , Alex Giacomini , Sergey A. Pavluchenko , Alexey Toporensky

A consistent description of gauge theories on coordinate dependent non-commutative (NC) space-time is a long-standing problem with a number of solutions, none of which is free from criticism. In this work, we discuss the approach proposed…

High Energy Physics - Theory · Physics 2019-04-23 Vladislav G. Kupriyanov

A comprehensive analysis of general relativistic spacetimes which admit a shear-free, irrotational and geodesic timelike congruence is presented. The equations governing the models for a general energy-momentum tensor are written down.…

General Relativity and Quantum Cosmology · Physics 2010-04-06 Alan A. Coley , Des J. Mc Manus

This study derives geometric, variational discretizations of continuum theories arising in fluid dynamics, magnetohydrodynamics (MHD), and the dynamics of complex fluids. A central role in these discretizations is played by the geometric…

Mathematical Physics · Physics 2015-05-20 Evan S. Gawlik , Patrick Mullen , Dmitry Pavlov , Jerrold E. Marsden , Mathieu Desbrun

We present a formalism for Newtonian multi-fluid hydrodynamics derived from an unconstrained variational principle. This approach provides a natural way of obtaining the general equations of motion for a wide range of hydrodynamic systems…

Fluid Dynamics · Physics 2009-11-07 Reinhard Prix

We study the implications of a noncommutative geometry of the minisuperspace variables for the FRW universe with a conformally coupled scalar field. The investigation is carried out by means of a comparative study of the universe evolution…

High Energy Physics - Theory · Physics 2009-11-10 G. D. Barbosa

A port-Hamiltonian model for compressible Newtonian fluid dynamics is presented in entirely coordinate-independent geometric fashion. This is achieved by use of tensor-valued differential forms that allow to describe describe the…

Fluid Dynamics · Physics 2021-05-05 Federico Califano , Ramy Rashad , Frederic P. Schuller , Stefano Stramigioli

Purpose: This essay is a retelling of general relativity in a language in which space-time geometry is expressed as a fluid. This trivial and useful reformulation gives 1) a non-perturbative covariant description of cosmological…

General Physics · Physics 2026-01-27 Albert Stebbins

We use covariant methods to analyse the nonlinear evolution of self-gravitating, non-relativistic media. The formalism is first applied to imperfect fluids, aiming at the kinematic effects of viscosity, before extended to inhomogeneous…

Astrophysics · Physics 2009-11-13 N. K. Spyrou , C. G. Tsagas