Transverse dynamics of a quasi-ideal binary fluid: mass asymmetry effects

The effect of mass asymmetry on the transverse dynamics of the binary symmetric mixture is investigated by combining the molecular dynamic (MD) simulations and parameter-free generalized collective mode (GCM) approach. The dependence of shear viscosity on the mass ratio of particles in the species is represented. A good agreement between results obtained using Green-Kubo formula and relation for correlation time of total momentum correlation function is found in a wide range of mass asymmetry. The behaviour of two lowest lying propagating modes is studied analytically within the four-variable approximation of GCM approach. It is established that if the mass ratio increases the propagating gap for shear waves becomes wider. However, if the concentration of heavy particles increases an opposite tendency is observed. The time correlation functions (TCFs) are calculated within this simplified four-variable scheme and a good agreement with results of direct MD simulations for these quantities is found.