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We study the dynamics near finite-time singularities of flat isotropic universes filled with two interacting but otherwise arbitrary perfect fluids. The overall dynamical picture reveals a variety of asymptotic solutions valid locally…

General Relativity and Quantum Cosmology · Physics 2015-06-04 Spiros Cotsakis , Georgia Kittou

We study curved isotropic cosmologies filled with two interacting fluids near their time singularities. We find that a number of these universes asymptote to flat limits in the sense that their asymptotic properties become indistinguishable…

General Relativity and Quantum Cosmology · Physics 2013-10-30 Spiros Cotsakis , Georgia Kittou

We investigate the case of two interacting fluids in homogeneous and isotropic cosmologies with a non-linear interaction term. The interaction term avoids the unrealistic form generally used in the literature, beginning with Tolman, in…

General Relativity and Quantum Cosmology · Physics 2020-02-18 John D. Barrow , Georgia Kittou

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 confined, quasi-two-dimensional guiding center plasma and a system of interacting line vortices in an ideal fluid are examples of Hamiltonian systems with infinite interaction distances. The existence of metastable states with negative…

Mathematical Physics · Physics 2010-11-09 Timothy D. Andersen

We investigate homogeneous and isotropic oscillating cosmologies with multiple fluid components. Transfer of energy between these fluids is included in order to model the effects of non-equilibrium behavior on closed universes. We find…

General Relativity and Quantum Cosmology · Physics 2008-11-26 T. Clifton , John D. Barrow

Motivated by cosmological applications for interacting matters, an extension of the action functional for relativistic fluids is proposed to incorporate the physics of non-adiabatic processes and chemical reactions. The former are…

General Relativity and Quantum Cosmology · Physics 2025-01-30 Damianos Iosifidis , Erik Jensko , Tomi S. Koivisto

In this paper a possibility of the accelerated expansion of the large scale universe with a varying polytropic fluid of a certain type is presented. About a special role of non-gravitational interactions between dark energy and dark matter,…

General Relativity and Quantum Cosmology · Physics 2017-07-14 Martiros Khurshudyan , Asatur Khurshudyan

We study the possible singularities of isotropic cosmological models that have a varying speed of light as well as a varying gravitational constant. The field equations typically reduce to two dimensional systems which are then analyzed…

General Relativity and Quantum Cosmology · Physics 2008-11-26 John Miritzis , Spiros Cotsakis

In this work, by considering an isentropic fluid-fluid interaction model with a large symmetric drag force, a commonly used simplified two-fluids flow model is justified as the asymptotic limit. Equations for each fluid component with an…

Fluid Dynamics · Physics 2022-03-11 Xin Liu

It is well known that Kasner-type cosmologies provide a useful framework for analyzing the three-dimensional anisotropic expansion because of the simplification of the anisotropic dynamics. In this paper relativistic multi-fluid Kasner-type…

General Relativity and Quantum Cosmology · Physics 2015-03-17 Mauricio Cataldo , Fabiola Arevalo , Patricio Mella

We investigate the emergent universe scenario in the presence of interacting fluids. The non-linear equation of state (EoS) considered in the general theory of relativity for obtaining emergent universe is effectively a cosmological model…

General Relativity and Quantum Cosmology · Physics 2015-05-20 B. C. Paul , A. S. Majumdar

We examine the dynamical implications of an interaction between some of the fluid components of the universe. We consider the combination of three matter components, one of which is a perfect fluid and the other two are interacting. The…

General Relativity and Quantum Cosmology · Physics 2009-10-31 Ana Nunes , Jose P. Mimoso , Tiago C. Charters

We give an asymptotic equivalent at infinity of the unbounded solutions of some boundary layer equations arising in fluid mechanics.

Classical Analysis and ODEs · Mathematics 2007-05-23 B. Brighi , J. -D. Hoernel

We show the existence of an infinite family of finite-time singularities in isotropically expanding universes which obey the weak, strong, and dominant energy conditions. We show what new type of energy condition is needed to exclude them…

General Relativity and Quantum Cosmology · Physics 2009-11-10 John D. Barrow , Christos G. Tsagas

Models of the universe with arbitrary (non gravitational) interaction between the components of the cosmic fluid: the phantom energy and the background, are investigated. A general form of the interaction that is inspired in scalar-tensor…

Astrophysics · Physics 2014-08-22 Ruben Curbelo , Tame Gonzalez , Genly León , Israel Quiros

In this note, we prove analytic bounds on the equation of state of a cosmological fluid composed of an arbitrary number of canonical scalars evolving in a negative multi-exponential potential. Because of the negative energy, the universe is…

General Relativity and Quantum Cosmology · Physics 2024-05-31 Gary Shiu , Flavio Tonioni , Hung V. Tran

We study homogeneous and isotropic cosmologies in a Weyl spacetime. We show that the field equations can be reduced to the Einstein equations with a two-fluid source and analyze the qualitative, asymptotic behavior of the models. Assuming…

General Relativity and Quantum Cosmology · Physics 2013-01-24 John Miritzis

We examine the evolution of a universe comprising two interacting fluids, which interact via a term proportional to the product of their densities. In the case of two matter fluids it is shown that the ratio of the densities tends to a…

General Relativity and Quantum Cosmology · Physics 2011-05-13 Sean Z. W. Lip

We consider interacting particle systems with unbounded interaction range on general countably infinite graphs $S$ and prove explicit non-asymptotic error bounds for approximations of the infinite-volume dynamics by systems of finitely many…

Probability · Mathematics 2026-03-24 Benedikt Jahnel , Jonas Köppl
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