Berlin 2012 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 29: Posters II
DY 29.32: Poster
Thursday, March 29, 2012, 17:00–19:00, Poster A
Motional patterns of particle trains in a microchannel — •Sebastian Reddig and Holger Stark — Institut für Theoretische Physik, Technische Universität Berlin, D-10623 Berlin, Germany
Microfluidic devices have emerged as powerful tools for manipulating, controlling, and analyzing various processes in chemistry, physics and biology. With the help of such devices one can make controlled studies on the influence of confinement and can easily drive suspended objects out of equilibrium, using a pressure driven Poiseuille flow. Thereby one can induce novel and intriguing dynamic structure formation in complex fluids, whose knowledge is essential, e.g., for developing tools to transport and sort particles on the micron scale.
We introduce a model for particle trains under the influence of a pressure driven flow, which are confined between two planar parallel walls. The colloids are neutrally buoyant and interact hydrodynamically via the solvent. We describe hydrodynamic interactions with the two-wall Green tensor that takes into account the no-slip condition at the walls1. We show that different initial conditions lead to different motional patterns, where the particle trains either form a propagating wave or one particle oscillates back and forth between its neighbors. We analyze the stability of these patterns and investigate how they depend on the ratio of colloid radius and channel width.
1Spherical particle in Poiseuille flow between planar walls, J. Chem. Phys, 121, 483 (2004).