Dresden 2003 – wissenschaftliches Programm

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SYSE: Simulation and experiment

SYSE 2: Poster (gemeinsam mit SYCN und CPP)

SYSE 2.8: Poster

Dienstag, 25. März 2003, 19:00–21:00, ZEU/250

Cross streamline migration of deformable objects in Poiseuille flow — •Andreas Arend, Diego Kienle, Gerald Ristow, and Walter Zimmermann — Theoretische Physik, Universität des Saarlandes, 66041 Saarbrücken

Polymers and vesicles are examples of deformable objects that migrate perpendicular to parallel stream lines under certain conditions, as reported with this contribution. The shear rate across the stream lines must be a function of space, such as for instance in a plane Poiseuille flow. The hydrodynamic interaction between different parts of the swimming object is crucial. The object must be asymmetric, either induced by the flow or spontaneously. The mechanism of migration is explained with a toy model of a rectangular “vesicle”. The effect is also confirmed by numerical calculations for simple objects such as a vesicles in two spatial dimensions, or for a few bead–springs models, including those for polymers. An example for a migrating polymer model that keeps its threedimensional shape without thermal fluctuations are four beads connected by springs with three neighbors forming a tetrahedron. Because of this described cross–stream–line migration the density of polymers in flowing polymer solutions can be an important rheological degree of freedom for flowing polymer solutions.