Static and dynamic properties of a particle-based algorithm for non-ideal fluids and binary mixtures

Abstract

A recently introduced particle-based model for fluid dynamics with effective excluded volume interactions is analyzed in detail. The interactions are modeled by means of stochastic multiparticle collisions which are biased and depend on local velocities and densities. Momentum and energy are exactly conserved locally. The isotropy and relaxation to equilibrium are analyzed and measured. It is shown how a discrete-time projection operator technique can be used to obtain Green-Kubo relations for the transport coefficients. Because of a large viscosity no long-time tails in the velocity auto-correlation and stress correlation functions were seen. Strongly reduced self-diffusion due to caging and an order/disorder transition is found at high collision frequency, where clouds consisting of at least four particles form a cubic phase. These structures were analyzed by measuring the pair-correlation function above and below the transition. Finally, the algorithm is extended to binary mixtures which phase-separate above a critical collision rate.