Dresden 2014 – wissenschaftliches Programm

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 37: Poster Session 2

CPP 37.25: Poster

Mittwoch, 2. April 2014, 15:00–19:00, P3

Dense Colloidal Suspensions in Microfluidic Flow — •Philipp Kanehl and Holger Stark — Institut für Theoretische Physik, TechnischeUniversität Berlin, D-10623 Berlin

Dense colloidal suspensions in a pressure driven flow accumulate in the center of the microchannel. Binary mixtures partially demix depending on their densities [1]. In very dense colloidal systems, one observes oscillations in the colloidal flow velocity which is attributed to transient jamming. The oscillations ultimately become irregular when increasing density further [2].

To develop a theoretical understanding of all these effects, we simulate hard disks under pressure-driven flow in two dimensions using the mesoscale simulation technique of Multi-Particle Collision Dynamics which is an efficient particle-based solver of the Navier-Stokes equation.

In our simulations, we reproduce the experimental observations that a binary suspension segregates into its two species. Whereas at equal densities the larger colloids accumulate in the center, this behavior is reversed when smaller colloids are in the majority and reach a critical density. In sufficiently dense, monodisperse suspensions we obtain the observed oscillations in narrow channels. We monitore both fluid and colloidal flow and thereby explore the role of fluid permeation. In addition, in the transient jamming regime we determine the size distribution for the jammed regions and also look for force chains.

[1] D. Semwogererea and E. R. Weeks, Phys. Fluids, 20, (2008).

[2] A. I. Campbell and M. D. Haw, Soft Matter 6, (2010).