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In (Commun Pure Appl Math 2(4):331-407, 1949), Grad proposed a Hermite series expansion for approximating solutions to kinetic equations that have an unbounded velocity space. However, for initial boundary value problems, poorly imposed…

Numerical Analysis · Mathematics 2023-03-01 Neeraj Sarna , Jan Giesselmann , Manuel Torrilhon

Far-from-equilibrium kinetic systems collapse onto a hydrodynamic attractor, traditionally approximated by a gradient expansion. While temporal gradient series are non-Borel summable and require transseries completions, the analytic…

Mathematical Physics · Physics 2026-04-07 Mahdi Kooshkbaghi

We derive a system of moment-based dynamical equations that describe the 1+1d space-time evolution of a cylindrically symmetric massive gas undergoing boost-invariant longitudinal expansion. Extending previous work, we introduce an explicit…

High Energy Physics - Phenomenology · Physics 2014-07-30 Mohammad Nopoush , Radoslaw Ryblewski , Michael Strickland

We show that the widely used relaxation time approximation to the relativistic Boltzmann equation contains basic flaws, being incompatible with microscopic and macroscopic conservation laws. We propose a new approximation that fixes such…

Nuclear Theory · Physics 2021-07-28 Gabriel S. Rocha , Gabriel S. Denicol , Jorge Noronha

The phenomenological textbook equations for the charge and heat transport are extensively used in a number of fields ranging from semiconductor devices to thermoelectricity. We provide a rigorous derivation of transport equations by solving…

Materials Science · Physics 2017-06-28 M. Battiato , V. Zlatic , K. Held

In this contribution we extend the Taylor expansion method proposed previously by one of us and establish equivalent partial differential equations of DDH lattice Boltzmann scheme at an arbitrary order of accuracy. We derive formally the…

Numerical Analysis · Mathematics 2015-05-13 François Dubois , Pierre Lallemand

We derive approximate iterative analytical solutions of the non-extensive Boltzmann transport equation in the relaxation time approximation. The approximate solutions almost overlap with the exact solution for a considerably wide range of…

Nuclear Theory · Physics 2023-06-27 Trambak Bhattacharyya

In this paper, we derive the quantum hydrodynamics models based on the moment closure of the Wigner equation. The moment expansion adopted is of the Grad type firstly proposed in \cite{Grad}. The Grad's moment method was originally…

Mathematical Physics · Physics 2015-06-05 Zhenning Cai , Yuwei Fan , Ruo Li , Tiao Lu , Yanli Wang

We explore the transition to hydrodynamics in a weakly-coupled model of quark-gluon plasma given by kinetic theory in the relaxation time approximation with conformal symmetry. We demonstrate that the gradient expansion in this model has a…

Nuclear Theory · Physics 2018-06-12 Michal P. Heller , Aleksi Kurkela , Michal Spalinski , Viktor Svensson

We study the local-in-time hydrodynamic limit of the relativistic Boltzmann equation using a Hilbert expansion. More specifically, we prove the existence of local solutions to the relativistic Boltzmann equation that are nearby the local…

Analysis of PDEs · Mathematics 2011-04-05 Jared Speck , Robert M. Strain

The relativistic method of moments is one of the most successful approaches to extract second order viscous hydrodynamics from a kinetic underlying background. The equations can be systematically improved to higher order, and they have…

Nuclear Theory · Physics 2019-02-20 L Tinti , G Vujanovic , J Noronha , U Heinz

We present an exact solution to the Boltzmann equation which describes a system undergoing boost-invariant longitudinal and azimuthally symmetric radial expansion for arbitrary shear viscosity to entropy density ratio. This new solution is…

High Energy Physics - Phenomenology · Physics 2014-12-30 Gabriel S. Denicol , Ulrich W. Heinz , Mauricio Martinez , Jorge Noronha , Michael Strickland

The quantum version of the Boltzmann transport equation (Wigner-Boltzmann equation) is a quite useful tool to investigate the effects of energy dissipation in quantum systems. Numerical approaches uses to be employed in order to stablish a…

Statistical Mechanics · Physics 2017-09-19 A. R. Fernandes Nt. , L. F. Santos

Thermalization in an expanding parton plasma is studied within the framework of Boltzmann equation in the absence of any mean fields. In particular, we study the time-dependence of the relaxation time to the lowest order in finite…

High Energy Physics - Phenomenology · Physics 2009-10-28 H. Heiselberg , Xin-Nian Wang

In this paper we obtain an analytical solution of the relativistic Boltzmann equation under the relaxation time approximation that describes the out-of-equilibrium dynamics of a radially expanding massless gas. This solution is found by…

High Energy Physics - Phenomenology · Physics 2016-01-06 Jorge Noronha , Gabriel S. Denicol

Analytical solutions to the microscopic Boltzmann equation are useful in testing the applicability and accuracy of macroscopic hydrodynamic theory. In this work, we present exact solutions of the relativistic Boltzmann equation, based on a…

Nuclear Theory · Physics 2024-04-15 Shile Chen , Shuzhe Shi

The dynamic response of an interacting electron system is determined by an extension of the relaxation-time approximation forced to obey local conservation laws for number, momentum and energy. A consequence of these imposed constraints is…

Strongly Correlated Electrons · Physics 2009-11-07 G. S. Atwal , N. W. Ashcroft

This paper presents a numerical approximation technique for the Boltzmann equation based on a moment system approximation in velocity dependence and a discontinuous Galerkin finite-element approximation in position dependence. The closure…

Computational Physics · Physics 2016-02-04 M. R. A. Abdelmalik , E. H. van Brummelen

Development of a new framework for derivation of order-by-order hydrodynamics from Boltzmann equation is necessary as the widely used Anderson-Witting formalism leads to violation of fundamental conservation laws when the relaxation-time…

Nuclear Theory · Physics 2022-06-07 Dipika Dash , Samapan Bhadury , Sunil Jaiswal , Amaresh Jaiswal

Usually, the relaxation times of a gas are estimated in the frame of the Boltzmann equation. In this paper, instead, we deal with the relaxation problem in the frame of the dynamical theory of Hamiltonian systems, in which the definition…

Mathematical Physics · Physics 2011-12-26 A. M. Maiocchi , A. Carati