Generalized transport coefficients for a disparate mass binary mixture

The transport coefficients for a disparate mass binary mixture are calculated as functions of the wave vector k and the frequency ω, taking as a starting point a kinetic model based on the Boltzmann equation. This allows us to study their behavior for short times and small distances when compared with the mean free time and the mean free path in the system. Such coefficients define the so-called generalized transport coefficients, which will give us an insight of the behavior of the system when relaxation effects are taken into account. In particular, a disparate mass binary mixture presents hierarchical relaxation and this fact is analyzed as well as its dependence on the mass quotient, which is the proper expansion parameter to express all results. An explicit example is given in the case of the hard sphere interaction for the He-Xe and Ar-Kr mixtures.