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We use the extended relaxation time approximation for the collision kernel, which incorporates a particle-energy dependent relaxation time, to derive second-order viscous hydrodynamics from the Boltzmann equation for a system of massless…

Nuclear Theory · Physics 2023-12-29 Dipika Dash , Sunil Jaiswal , Samapan Bhadury , Amaresh Jaiswal

Hydrodynamics can be formulated as the gradient expansion of conserved currents in terms of the fundamental fields describing the near-equilibrium fluid flow. In the relativistic case, the Navier-Stokes equations follow from the…

High Energy Physics - Theory · Physics 2017-10-06 Sašo Grozdanov , Nikolaos Kaplis

The first order hydrodynamic evolution equations for the shear stress tensor, the bulk viscous pressure and the charge current have been studied for a system of quarks and gluons, with a non-vanishing quark chemical potential and finite…

High Energy Physics - Phenomenology · Physics 2020-07-16 Samapan Bhadury , Manu Kurian , Vinod Chandra , Amaresh Jaiswal

A new formulation of second-order viscous hydrodynamics, based on an expansion around a locally anisotropic momentum distribution, is presented. It generalizes the previously developed formalism of anisotropic hydrodynamics (aHydro) to…

Nuclear Theory · Physics 2015-06-22 Ulrich W. Heinz , Dennis Bazow , Michael Strickland

Derivations of relativistic second-order dissipative hydrodynamic equations have relied almost exclusively on the use of Grad's 14-moment approximation to write $f(x,p)$, the nonequilibrium distribution function in the phase space. Here we…

Nuclear Theory · Physics 2014-06-16 Rajeev S. Bhalerao , Amaresh Jaiswal , Subrata Pal , V. Sreekanth

Non-equilibrium dynamics for relativistic fluid or quark gluon plasma (QGP) have already been calculated earlier upto third order using both kinetic and thermodynamic approaches. Calculations presented in this manuscript are based on…

Nuclear Theory · Physics 2020-09-09 Mohammed Younus , Azwinndini Muronga

Comparison of hydrodynamic calculations with experimental data inevitably requires a model for converting the fluid to particles. In this work, nonlinear $2\to 2$ kinetic theory is used to assess the overall accuracy of various shear…

Generalizing the collision term in the relativistic Boltzmann equation to include nonlocal effects, and using Grad's 14-moment approximation for the single-particle distribution function, we derive evolution equations for the relativistic…

Nuclear Theory · Physics 2013-03-13 Amaresh Jaiswal , Rajeev S. Bhalerao , Subrata Pal

Anisotropic hydrodynamics improves upon standard dissipative fluid dynamics by treating certain large dissipative corrections non-perturbatively. Relativistic heavy-ion collisions feature two such large dissipative effects: (i) Strongly…

Nuclear Theory · Physics 2018-06-06 M. McNelis , D. Bazow , U. Heinz

We investigate the microscopic origin of the relaxation time coefficient in relativistic fluid dynamics. We show that the extraction of the shear viscosity relaxation time via the gradient expansion is ambiguous and in general fails to give…

Nuclear Theory · Physics 2015-05-30 G. S. Denicol , J. Noronha , H. Niemi , D. H. Rischke

We calculate the $\delta f$ correction to the one particle distribution function in presence of magnetic field and non-zero shear viscosity within the relaxation time approximation. The $\delta f$ correction is found to be electric charge…

Nuclear Theory · Physics 2019-09-04 Payal Mohanty , Ashutosh Dash , Victor Roy

We present a complete formulation of second-order (2+1)-dimensional anisotropic hydrodynamics. The resulting framework generalizes leading-order anisotropic hydrodynamics by allowing for deviations of the one-particle distribution function…

Nuclear Theory · Physics 2014-11-26 Dennis Bazow , Ulrich W. Heinz , Michael Strickland

Based on the exact solution of Boltzmann kinetic equation in the relaxation-time approximation, the precision of the two most recent formulations of relativistic second-order non-conformal viscous hydrodynamics (14-moment approximation and…

Nuclear Theory · Physics 2015-06-11 Radoslaw Ryblewski

We compute the temporal evolution of the pressure anisotropy and bulk pressure of a massive gas using second-order viscous hydrodynamics and anisotropic hydrodynamics. We then compare our results with an exact solution of the Boltzmann…

High Energy Physics - Phenomenology · Physics 2014-10-16 Gabriel S. Denicol , Wojciech Florkowski , Radoslaw Ryblewski , Michael Strickland

A novel formulation of second-order relativistic viscous fluid dynamics based on the effective Boltzmann equation for quasi-particles with medium-dependent masses is briefly reviewed.~The evolution equations for the shear and bulk…

Nuclear Theory · Physics 2017-08-07 Radoslaw Ryblewski

We obtain a formal integral solution to the 3+1 D Boltzmann Equation in relaxation time approximation. The gradient series obtained from this integral solution contains exponentially decaying non-hydrodynamic terms. It is shown that this…

Nuclear Theory · Physics 2024-05-24 Reghukrishnan Gangadharan , Victor Roy

We exactly solve the relaxation-time approximation Boltzmann equation for a system which is transversely homogeneous and undergoing boost-invariant longitudinal expansion. We compare the resulting exact numerical solution with approximate…

Nuclear Theory · Physics 2013-09-27 Wojciech Florkowski , Radoslaw Ryblewski , Michael Strickland

Using Grad's method, we calculate the entropy production and derive a formula for the second-order shear viscosity coefficient in a one-dimensionally expanding particle system, which can also be considered out of chemical equilibrium. For a…

High Energy Physics - Phenomenology · Physics 2010-04-21 Andrej El , Zhe Xu , Carsten Greiner , Azwinndini Muronga

We interpret as shear viscosity the anisotropic pressure that emerges in inhomogeneous spherically symmetric spacetimes described by the Lemaitre-Tolman-Bondi (LTB) metric in a comoving frame. By assuming that local isotropic pressure and…

General Relativity and Quantum Cosmology · Physics 2008-12-24 Roberto A Sussman

Starting with the relativistic Boltzmann equation where the collision term is generalized to include nonlocal effects via gradients of the phase-space distribution function, and using Grad's 14-moment approximation for the distribution…

Nuclear Theory · Physics 2013-05-23 Amaresh Jaiswal , Rajeev S. Bhalerao , Subrata Pal