Construction of Normal Discrete Velocity Models of the Boltzmann Equation

Abstract

Discretization methods have been developed on the idea of replacing the original Boltzmann equation (BE) by a finite set of nonlinear hyperbolic PDEs corresponding to the densities linked to a suitable finite set of velocities. One open problem related to the discrete BE is the construction of normal (fulfilling only physical conservation laws) discrete velocity models (DVMs). In many papers on DVMs, authors postulate from the beginning that a finite velocity space with such properties is given and after that study the discrete BE. Our aim is not to study the equations for DVMs, but to discuss all possible choices of finite sets of velocities satisfying this type of restrictions. Using our previous results, i.e. the general algorithm for the construction of normal discrete kinetic models (DKMs), we develop and implement an algorithm for the particular case of DVMs of the BE and give a complete classification for models with small number n of velocities (n ≤ 10).