Dresden 2011 – scientific programme
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DY: Fachverband Dynamik und Statistische Physik
DY 10: Posters I
DY 10.3: Poster
Monday, March 14, 2011, 17:00–19:00, P4
Migration of semiflexible polymers in a pressure driven flow — •Sebastian Reddig and Holger Stark — Institut für Theoretische Physik, TU-Berlin
Experiments on single α-actin filaments in microchannels showed that the steady state center-of-mass probability density is nonuniformly distributed across the channel under the influence of a Poiseuille flow1. Depletion layers near the walls and in the centerline were observed. Hydrodynamic interactions between the polymer and the walls lead to migration away from the walls, while a spatially varying diffusion coefficient resulting from a locally varying polymer conformation drives the polymer away from the centerline. These competing mechanisms give the observed bimodal distribution.
We introduce a model for a semiflexible polymer under the influence of a pressure driven flow, which is confined between two parallel planar walls. The polymer is modelled by a bead-spring chain including a bending potential. We describe hydrodynamic interactions between the beads with the two-wall Green tensor. It was derived by R.B. Jones2 and takes into account the no-slip boundary condition at the walls.
Brownian dynamics simulations for our model reproduce the same behavior as in experiments, in particular, the bimodal distribution. We demonstrate how velocity of the Poiseuille flow and bending rigidity influence this distribution and also study end-to-end distance and the orientation of the polymer in the microchannel.
1 D. Steinhauser, S. Köster, H. Stark, and T. Pfohl, submitted.
2 R.B. Jones, J. Chem. Phys, 121, 483 (2004).