Dynamic Regimes of Fluids Simulated by Multi-Particle-Collision Dynamics

Ripoll, M.; Mussawisade, K.; Gompper, G.; Winkler, R. G.

doi:10.1103/PhysRevE.72.016701

Journal Article

PreJuSER-47063

Dynamic Regimes of Fluids Simulated by Multi-Particle-Collision Dynamics

Ripoll, M.FZJ* ; Mussawisade, K.FZJ* ; Winkler, R. G.FZJ* ; Gompper, G.FZJ*

2005
APS College Park, Md.

Physical review / E 72(1), 016701 (2005) [10.1103/PhysRevE.72.016701]

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Please use a persistent id in citations: http://hdl.handle.net/2128/1523 doi:10.1103/PhysRevE.72.016701

Abstract: We investigate the hydrodynamic properties of a fluid simulated with a mesoscopic solvent model. Two distinct regimes are identified, the "particle regime" in which the dynamics is gaslike and the "collective regime" where the dynamics is fluidlike. This behavior can be characterized by the Schmidt number, which measures the ratio between viscous and diffusive transport. Analytical expressions for the tracer diffusion coefficient, which have been derived on the basis of a molecular-chaos assumption, are found to describe the simulation data very well in the particle regime, but important deviations are found in the collective regime. These deviations are due to hydrodynamic correlations. The model is then extended in order to investigate self-diffusion in colloidal dispersions. We study first the transport properties of heavy pointlike particles in the mesoscopic solvent, as a function of their mass and number density. Second, we introduce excluded-volume interactions among the colloidal particles and determine the dependence of the diffusion coefficient on the colloidal volume fraction for different solvent mean-free paths. In the collective regime, the results are found to be in good agreement with previous theoretical predictions based on Stokes hydrodynamics and the Smoluchowski equation.

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