Hermite spectral method for multi-species Boltzmann equation

We introduce a numerical scheme for the full multi-species Boltzmann equation based on Hermite spectral method. With proper choice of expansion centers different species, practical algorithm is derived to evaluate complicated binary collision operator. New models are built by combining quadratic model and simple BGK under framework method, which enables us balance computational cost accuracy. Several experiments implemented validate dramatic efficiency this new Moreover, we can handle problems with as many 100 far beyond capability state-of-art algorithms.