English
Related papers

Related papers: Relaxation time approximations in PAOFLOW 2.0

200 papers

We reformulate the Boltzmann equation in the relaxation time approximation undergoing Bjorken flow in terms of a novel partial differential equation for the generating function of the moments of the distribution function. This is used to…

Nuclear Theory · Physics 2024-01-15 Inês Aniceto , Jorge Noronha , Michał\ Spaliński

We propose a two-population lattice Boltzmann model on standard lattices for the simulation of compressible flows. The model is fully on-lattice and uses the single relaxation time Bhatnagar-Gross-Krook kinetic equations along with…

Fluid Dynamics · Physics 2021-11-24 M. H. Saadat , S. A. Hosseini , B. Dorschner , I. V. Karlin

A general lattice Boltzmann method for simulation of fluids with tailored transport coefficients is presented. It is based on the recently introduced quasi-equilibrium kinetic models, and a general lattice Boltzmann implementation is…

Statistical Mechanics · Physics 2007-05-23 S. Ansumali , S. Arcidiacono , S. Chikatamarla , N. I. Prasianakis , A. N. Gorban , I. V. Karlin

We introduce a generalised relaxation-time-approximation form of the collision term in the Boltzmann kinetic equation that allows for using different relaxation times for elastic and inelastic collisions. The efficacy of the proposed…

Nuclear Theory · Physics 2016-06-15 Wojciech Florkowski , Radoslaw Ryblewski

The relaxation time approximation (RTA) of the kinetic Boltzmann equation is likely the simplest window into the microscopic properties of collective real-time transport. Within this framework, we analytically compute all retarded two-point…

High Energy Physics - Theory · Physics 2024-07-23 Matej Bajec , Sašo Grozdanov , Alexander Soloviev

We systematically derived hydrodynamic equations and transport coefficients for a class of multi-speed lattice Boltzmann models in D dimensions, using the multi-scale technique. The constitutive relation of physical fluid is recovered by a…

comp-gas · Physics 2008-02-03 Yu Chen , Hirotada Ohashi , Mamoru Akiyama

We give a detailed derivation of the second-order (local) hydrodynamics for Boltzmann equation with an external force by using the renormalization group method. In this method, we solve the Boltzmann equation faithfully to extract the…

Quantum Gases · Physics 2016-04-27 Yuta Kikuchi , Kyosuke Tsumura , Teiji Kunihiro

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

We present a method for reconstructing the phonon relaxation time distribution $\tau_{\omega}= \tau (\omega)$ (including polarization) in a material from thermal spectroscopy data. The distinguishing feature of this approach is that it does…

Other Condensed Matter · Physics 2018-05-30 Mojtaba Forghani , Nicolas G. Hadjiconstantinou

This paper proposes a scalable lattice-Boltzmann computational framework (SBoTFlow) for simulations of flexible moving objects in an incompressible fluid flow. Behavior of fluid flow formed from moving boundaries of flexible-object motions…

Fluid Dynamics · Physics 2024-02-08 Duc V. Nguyen , Dung V. Duong

In this paper, we study all transport coefficients of second-order dissipative fluid dynamics derived by V. E. Ambrus et al. [Phys. Rev. D 106, 076005 (2022)] from the relativistic Boltzmann equation in the relaxation-time approximation for…

Nuclear Theory · Physics 2024-04-30 Victor Ambrus , Etele Molnár , Dirk H. Rischke

A jump-diffusion process along with a particle scheme is devised as an accurate and efficient particle solution to the Boltzmann equation. The proposed process (hereafter Gamma-Boltzmann model) is devised to match the evolution of all…

Computational Physics · Physics 2023-08-09 Fabian Mies , Mohsen Sadr , Manuel Torrilhon

Conventional lattice Boltzmann models for the simulation of fluid dynamics are restricted by an error in the stress tensor that is negligible only for vanishing flow velocity and at a singular value of the temperature. To that end, we…

Fluid Dynamics · Physics 2021-04-28 M. H. Saadat , B. Dorschner , I. V. Karlin

Explicit expressions for all the transport coefficients have recently been found for a trapped Bose condensed gas at finite temperatures. These transport coefficients are used to define the characteristic relaxation times, which determine…

Statistical Mechanics · Physics 2009-11-07 T. Nikuni , A. Griffin

A detailed analysis is presented to demonstrate the capabilities of the lattice Boltzmann method. Thorough comparisons with other numerical solutions for the two-dimensional, driven cavity flow show that the lattice Boltzmann method gives…

comp-gas · Physics 2009-10-22 Shuling Hou , Qisu Zou , Shiyi Chen , Gary D. Doolen , Allen C. Cogley

This work demonstrates a first-principles-based approach to obtaining finite temperature thermal and electronic transport properties which can be employed to model and understand mesoscale structural evolution during electronic, magnetic,…

We use the Boltzmann equation in the relaxation time approximation to study the expansion of a dilute Fermi gas at unitarity. We focus, in particular, on the approach to the hydrodynamic limit. Our main finding are: i) In the regime that…

Statistical Mechanics · Physics 2013-05-29 Kevin Dusling , Thomas Schaefer

Lattice Boltzmann simulations of liquid-gas systems are believed to be restricted to modest density ratios of less than 10. In this article we show that reducing the speed of sound and, just as importantly, the interfacial contributions to…

Soft Condensed Matter · Physics 2007-05-23 A. J. Wagner , C. M. Pooley

This paper presents a numerical study of flow through static random assemblies of monodisperse, spherical particles. A lattice Boltzmann approach based on a two relaxation time collision operator is used to obtain reliable predictions of…

Fluid Dynamics · Physics 2014-10-08 Simon Bogner , Swati Mohanty , Ulrich Rüde

We propose a multiple relaxation time Boltzmann equation collision model by systematically assigning a separate relaxation time to each of the central moments of the distribution function. The Chapman-Enskog calculation leads to correct…

Computational Physics · Physics 2020-10-06 Xiaowen Shan