Volume 80, Number 4, November 2007
Article Number 40010
Number of page(s) 6
Section General
Published online 23 October 2007
EPL, 80 (2007) 40010
DOI: 10.1209/0295-5075/80/40010

Mesoscopic model for the fluctuating hydrodynamics of binary and ternary mixtures

E. Tüzel, G. Pan, T. Ihle and D. M. Kroll

Department of Physics, North Dakota State University - P.O. Box 5566, Fargo, ND 58105, USA

received 18 July 2007; accepted in final form 18 September 2007; published November 2007
published online 23 October 2007

A recently introduced particle-based model for fluid dynamics with continuous velocities is generalized to model immiscible binary mixtures. Excluded-volume interactions between the two components are modeled by stochastic multiparticle collisions which depend on the local velocities and densities. Momentum and energy are conserved locally, and entropically driven phase separation occurs for high collision rates. An explicit expression for the equation of state is derived, and the concentration dependence of the bulk free energy is shown to be the same as that of the Widom-Rowlinson model. Analytic results for the phase diagram are in excellent agreement with simulation data. Results for the interfacial tension obtained from the analysis of the capillary wave spectrum of a two-dimensional droplet agree with measurements based on the Laplace's equation. The introduction of "amphiphilic" dimers makes it possible to model the phase behavior and dynamics of ternary surfactant mixtures.

02.70.Ns - Molecular dynamics and particle methods.
47.11.-j - Computational methods in fluid dynamics.
05.40.-a - Fluctuation phenomena, random processes, noise, and Brownian motion.

© Europhysics Letters Association 2007