Berlin 2008 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 18: Soft matter

DY 18.2: Vortrag

Mittwoch, 27. Februar 2008, 14:30–14:45, MA 001

Mesoscale, particle-based simulations of binary mixtures and microemulsions — •Thomas Ihle and Daniel Kroll — Department of Physics, North Dakota State University, Fargo, ND, 58105, USA

An appealing algorithm for complex fluids introduced by Malevanets and Kapral, often called Stochastic Rotation Dynamics (SRD), describes a fluid by means of particles which undergo efficient multi-particle collisions. The algorithm has been successfully applied to study the behavior of polymers, colloids and vesicles.

Here, we use a recent generalization of this algorithm for binary mixtures [1,2]. We present results for the demixing of a mixture such as the phase diagram, interface fluctuations and the surface tension of a droplet. We show how Ginzburg-Landau free energy functionals including gradient terms can be derived from the microscopic collision rules. Expressions for the equation of state and the phase diagram are shown to be in excellent agreement with numerical results.

To describe microemulsions, a third phase of surfactant molecules is introduced which consists of rigid objects. We show how objects of arbitrary shape can be efficiently embedded in the SRD-fluid. The phase diagram and results for emulsification will be presented.

[1] T. Ihle, E. Tuzel, D.M. Kroll, Europhys. Lett. 73 (2006) 664.

[2] E. Tuzel, G. Pan, T. Ihle and D. M. Kroll, Europhys. Lett. 80 (2007) 40010.