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In this paper, a lattice Boltzmann (LB) model with double distribution functions is proposed for two-phase flow in porous media where one distribution function is used for pressure governed by the Poisson equation, and the other is applied…

Computational Physics · Physics 2018-08-24 Zhenhua Chai , Hong Liang , Rui Du , Baochang Shi

We study the bosonic Boltzmann-Nordheim kinetic equation, which describes the kinetic regime of weakly interacting bosons with s-wave scattering only. We consider a spatially homogeneous fluid with an isotropic momentum distribution. The…

Mesoscale and Nanoscale Physics · Physics 2008-09-29 Herbert Spohn

We give an explicit description of the spectral closure for the three-dimensional linear Boltzmann-BGK equation in terms of the macroscopic fields, density, flow velocity and temperature. This results in a new linear fluid dynamics model…

Analysis of PDEs · Mathematics 2023-06-13 Florian Kogelbauer , Ilya Karlin

In this paper, we give an overview of the results established in [3] which provides the first rigorous derivation of hydrodynamic equations from the Boltzmann equation for inelastic hard spheres in 3D. In particular, we obtain a new system…

Analysis of PDEs · Mathematics 2022-05-04 Ricardo J. Alonso , Bertrand Lods , Isabelle Tristani

The influence and validity of wall boundary conditions for non-equilibrium fluid flows described by the Boltzmann equation remains an open problem. The substantial computational cost of directly solving the Boltzmann equation has limited…

Fluid Dynamics · Physics 2024-01-02 Tarik Dzanic , Freddie D. Witherden , Luigi Martinelli

Many features of granular media can be modeled by a fluid of hard spheres with inelastic collisions. Under rapid flow conditions, the macroscopic behavior of grains can be described through hydrodynamic equations accounting for dissipation…

Statistical Mechanics · Physics 2007-05-23 V. Garzo , J. W. Dufty

We derive the second-order hydrodynamic equation and the microscopic formulae of the relaxation times as well as the transport coefficients systematically from the relativistic Boltzmann equation. Our derivation is based on a novel…

High Energy Physics - Phenomenology · Physics 2016-02-01 Kyosuke Tsumura , Yuta Kikuchi , Teiji Kunihiro

The hydrodynamic equations for a model of a confined quasi-two-dimensional gas of smooth inelastic hard spheres are derived from the Boltzmann equation for the model, using a generalization of the Chapman-Enskog method. The heat and…

Statistical Mechanics · Physics 2015-06-11 J. Javier Brey , V. Buzón , P. Maynar , M. I. García de Soria

We consider a beam model representing the transverse deflections of a one dimensional elastic structure immersed in an axial fluid flow. The model includes a nonlinear elastic restoring force, with damping and non-conservative terms…

Analysis of PDEs · Mathematics 2019-04-22 Jason Howell , Katelynn Huneycutt , Justin T. Webster , Spencer Wilder

Within the framework of the post-Newtonian $2\frac12$ approximation theory, a kinetic theory for relativistic gases in the presence of gravitational fields is developed. The Boltzmann equation and the equilibrium Maxwell-J\"uttner…

General Relativity and Quantum Cosmology · Physics 2026-05-01 Gilberto M. Kremer

Considering a gas of self-propelled particles with binary interactions, we derive the hydrodynamic equations governing the density and velocity fields from the microscopic dynamics, in the framework of the associated Boltzmann equation.…

Statistical Mechanics · Physics 2009-10-09 Eric Bertin , Michel Droz , Guillaume Grégoire

Lattice Boltzmann methods are usually derived under the assumption of isotropy. In this work, we present a derivation of a Lattice Boltzmann method for anisotropic fluid flow. Starting from an anisotropic equilibrium distribution, we show a…

Fluid Dynamics · Physics 2026-05-27 Benjamin Kellers , Julius Weinmiller , Arnulf Latz , Timo Danner

In order to find reliable and efficient numerical approximation schemes, we suggest to identify the Functional Renormalization Group flow equations of one-particle irreducible two-point functions as Hamilton-Jacobi(-Bellman)-type partial…

High Energy Physics - Theory · Physics 2025-12-30 Adrian Koenigstein , Martin J. Steil , Stefan Floerchinger

We consider a boundary value problem for the system of equations describing the stationary motion of a viscous nonhomogeneous asymmetric fluid in a bounded planar domain having a $C^2$ boundary. We use a stream-function formulation after…

Analysis of PDEs · Mathematics 2011-08-02 Fábio Vitoriano Silva

The solutions of the one-dimensional homogeneous nonlinear Boltzmann equation are studied in the QE-limit (Quasi-Elastic; infinitesimal dissipation) by a combination of analytical and numerical techniques. Their behavior at large velocities…

Statistical Mechanics · Physics 2007-07-03 Alain Barrat , E. Trizac , M. H. Ernst

Nonthermal fixed points of the dynamics of a dilute degenerate Bose gas far from thermal equilibrium are analyzed in two and three spatial dimensions. Universal power-law distributions, previously found within a nonperturbative…

Quantum Gases · Physics 2012-05-02 Boris Nowak , Jan Schole , Dénes Sexty , Thomas Gasenzer

Using a continuous unitary transformation recently proposed by Wegner \cite{Wegner} together with an approximation that neglects irrelevant contributions, we obtain flow equations for Hamiltonians. These flow equations yield a diagonal or…

Condensed Matter · Physics 2009-10-22 Stephan Kehrein , Andreas Mielke

This paper establishes a sufficient condition for guaranteeing power flow solvability in distribution grids with inverter-based resources (IBRs) operating under IEEE 1547 compliant Volt-Var control. While designed to improve voltage…

Systems and Control · Electrical Eng. & Systems 2026-04-21 Taha Saeed Khan , Hamidreza Nazaripouya

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

After a short elementary introduction to the exact renormalization group for the effective action, I discuss a particular truncation of the hierarchy of flow equations that allows for the determination of the full momentum of the $n$-point…

Statistical Mechanics · Physics 2011-10-18 Jean-Paul Blaizot