scholarly journals Multifluid Modelling of Relativistic Radiation Hydrodynamics

Symmetry ◽  
2020 ◽  
Vol 12 (9) ◽  
pp. 1543
Author(s):  
Lorenzo Gavassino ◽  
Marco Antonelli ◽  
Brynmor Haskell
Keyword(s):  
Heat Conduction ◽  
Bulk Viscosity ◽  
Dissipative Systems ◽  
Universal Theory ◽  
Radiation Hydrodynamics ◽  
Hydrodynamic Equations ◽  
Relativistic Fluid ◽  
Microscopic Interpretation ◽  
Universal Applicability ◽  
Fundamental Equations

The formulation of a universal theory for bulk viscosity and heat conduction represents a theoretical challenge for our understanding of relativistic fluid dynamics. Recently, it was shown that the multifluid variational approach championed by Carter and collaborators has the potential to be a general and natural framework to derive (hyperbolic) hydrodynamic equations for relativistic dissipative systems. Furthermore, it also allows keeping direct contact with non-equilibrium thermodynamics, providing a clear microscopic interpretation of the elements of the theory. To provide an example of its universal applicability, in this paper we derive the fundamental equations of the radiation hydrodynamics directly in the context of Carter’s multifluid theory. This operation unveils a novel set of thermodynamic constraints that must be respected by any microscopic model. Then, we prove that the radiation hydrodynamics becomes a multifluid model for bulk viscosity or heat conduction in some appropriate physical limits.

scholarly journals Bulk viscosity and relaxation time of causal dissipative relativistic fluid dynamics

2011 ◽  
Vol 83 (2) ◽  
Author(s):  
Xu-Guang Huang ◽  
Takeshi Kodama ◽  
Tomoi Koide ◽  
Dirk H. Rischke
Keyword(s):  
Fluid Dynamics ◽  
Relaxation Time ◽  
Bulk Viscosity ◽  
Relativistic Fluid Dynamics ◽  
Relativistic Fluid

The Construction of a Conservative Radiation Hydrodynamics Algorithm in Two-Dimensional Spherical Geometry

2019 ◽  
Vol 141 (10) ◽  
Author(s):  
Zhiwei Lin ◽  
Shaoen Jiang ◽  
Lu Zhang
Keyword(s):  
Radiation Transport ◽  
Spherical Geometry ◽  
Artificial Viscosity ◽  
Radiation Hydrodynamics ◽  
Two Dimensional ◽  
Hydrodynamic Equations ◽  
Spherical Coordinates ◽  
Spatial Control ◽  
Lagrangian Hydrodynamics ◽  
Control Volumes

Abstract This paper presents the construction of a conservative radiation hydrodynamics algorithm in two-dimensional (2D) spherical geometry. First, we discretize the radiation transport equation (RTE) in that geometry. The discretization preserves the conservation of photons by integrating the original RTE in 2D spherical coordinates over both angular and spatial control volumes. Some numerical results are provided to verify the discretization for both optically thin and thick circumstances. Second, we formulate the staggered Lagrangian hydrodynamics in that geometry. The formulation preserves the conservation of mass, momentum, and energy by integrating the original hydrodynamic equations in 2D spherical coordinates over their respective control volumes. The original edge-centered artificial viscosity in 2D cylindrical geometry is also extended to be capable of capturing shock waves in 2D spherical geometry. Several 2D benchmark cases are provided to verify the scheme. The subsequent construction of the conservative radiation hydrodynamics algorithm is accomplished by the combination of the staggered Lagrangian hydrodynamics scheme and the solution of the RTE in 2D spherical geometry. Several 2D problems are calculated to verify our radiation hydrodynamics algorithm at the end.

scholarly journals ON THE ROLE OF VISCOSITY IN EARLY COSMOLOGY

2008 ◽  
Vol 23 (08) ◽  
pp. 1248-1252
Author(s):  
NAKIA CARLEVARO ◽  
GIOVANNI MONTANI
Keyword(s):  
Energy Density ◽  
Power Law ◽  
Bulk Viscosity ◽  
Viscosity Coefficient ◽  
Hydrodynamic Equations ◽  
Restricted Domain ◽  
Asymptotic Approach ◽  
Cosmological Singularity ◽  
Second Order In Time

We present a discussion of the effects induced by bulk viscosity on the very early Universe stability. The viscosity coefficient is assumed to be related to the energy density ρ via a power-law of the form ζ = ζ0ρs (where ζ0, s = const.) and the behavior of the density contrast in analyzed. In particular, we study both Einstein and hydrodynamic equations up to first and second order in time in the so-called quasi-isotropic collapsing picture near the cosmological singularity. As a result, we get a power-law solution existing only in correspondence to a restricted domain of ζ0. The particular case of pure isotropic FRW dynamics is then analyzed and we show how the asymptotic approach to the initial singularity admits an unstable collapsing picture.

TILTED BIANCHI TYPE-V BAROTROPIC FLUID COSMOLOGICAL MODELS WITH VARIABLE BULK VISCOSITY IN GENERAL RELATIVITY

2011 ◽  
Vol 26 (24) ◽  
pp. 4299-4310
Author(s):  
RAJ BALI ◽  
PRAMILA KUMAWAT ◽  
SHALINI SHARMA
Keyword(s):  
General Relativity ◽  
Heat Conduction ◽  
Bulk Viscosity ◽  
Bianchi Type ◽  
Deterministic Model ◽  
Cosmological Models ◽  
Barotropic Fluid ◽  
Type V ◽  
The Universe ◽  
Bianchi Type V

Tilted Bianchi type-V barotropic fluid cosmological models with heat conduction and variable bulk viscosity is investigated. To get the deterministic model of the universe, we have assumed two conditions: (i) A = (BC)nand (ii) ζθ = const where A, B, C are metric potentials, n is a constant, ζ the coefficient of bulk viscosity, θ the expansion in the model. The behavior of the model in presence and absence of bulk viscosity and singularities in the model are discussed. Some thermodynamic relations and physical aspects of the model related to the observation on the present day universe are also discussed.

Radiation Hydrodynamics of Accreting Magnetic White Dwarfs

1996 ◽  
Vol 158 ◽  
pp. 199-202 ◽  
Author(s):  
K. Beuermann ◽  
U. Woelk
Keyword(s):  
Mass Flow ◽  
White Dwarfs ◽  
Radiation Hydrodynamics ◽  
Hydrodynamic Equations ◽  
Flow Rates ◽  
One Dimensional ◽  
Cyclotron Radiation ◽  
Wide Range ◽  
Mass Flow Rates ◽  
Two Fluid

AbstractWe solved the stationary one-dimensional two-fluid radiation hydrodynamic equations including cyclotron radiation for a wide range of mass flow rates. Here, we discuss the implications for accretion phenomena on the white dwarfs in AM Her binaries.

On the transport properties of a Van der Waals gas near the critical point

1968 ◽  
Vol 46 (24) ◽  
pp. 2821-2841 ◽  
Author(s):  
Luis de Sobrino
Keyword(s):  
Thermal Conductivity ◽  
Time Dependence ◽  
Critical Point ◽  
Bulk Viscosity ◽  
Shear Viscosity ◽  
Van Der Waals ◽  
Transport Coefficients ◽  
Hydrodynamic Equations ◽  
Van Der Waals Gas ◽  
Critical Fluctuations

A calculation of the critical anomalies of the transport coefficients of a simple fluid based on a microscopic model of a nonequilibrium Van der Waals gas is presented. It is found that, in the gas region, the anomalous bulk viscosity behaves as (T – Tc)−2. Both the anomalous thermal conductivity and shear viscosity behave as In (T – Tc)−1, but the anomaly in the shear viscosity is much smaller than the anomaly in the thermal conductivity. The results appear to indicate that previous calculations, in which the time dependence of the critical fluctuations is obtained from hydrodynamic equations, are not valid.

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