Raúl Machado | Searcharxiv

arXiv2013

On the moment system and a flexible Prandtl number

The Maxwell-Boltzmann moment system can be seen as a particular case of a mathematically more general moment system proposed by Machado in Ref [1]. This last moment system, whose integral generating form and a suggested continuous distribution are presented here, is used in this letter to theoretically show (one of) its usefulness: A flexible Prandtl number can be obtained in both the Boltzmann equation and in the lattice Boltzmann equation with a conventional single relaxation time Bhatnagar-Gross-Krook collision model.

physics.flu-dyn↗

arXiv2013

On the Generalized Hermite-Based Lattice Boltzmann Construction, Lattice Sets, Weights, Moments, Distribution Functions and High-Order Models

The influence of the use of the generalized Hermite polynomial on the Hermite-based lattice Boltzmann (LB) construction approach, lattice sets, the thermal weights, moments and the equilibrium distribution function (EDF) are addressed. A new moment system is proposed. The theoretical possibility to obtain a high-order Hermite-based LB model capable to exactly match some first hydrodynamic moments thermally 1) on-Cartesian lattice, 2) with thermal weights in the EDF, 3) whilst the highest possible hydrodynamic moments that are exactly matched are obtained with the shortest on-Cartesian lattice sets with some fixed real-valued temperatures, is also analyzed. Keywords: Lattice Boltzmann, fluid dynamics, kinetic theory, distribution function

cs.CE↗