Dresden 2009 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 28: Pattern formation in colloidal and granular systems II
DY 28.9: Vortrag
Freitag, 27. März 2009, 12:30–12:45, HÜL 386
Dynamical polarization and unusual flow response in the shear flow of dipolar colloidal rod suspensions — •Sebastian Heidenreich1, Siegfried Hess1, and Sabine H. L. Klapp2 — 1Institute für Theoretische Physik, TU Berlin, 10623, Germany — 2Institut für Theoretische Physik, FU Berlin, 14195 Berlin, Germany
The flow properties of colloidal rod suspensions are strongly affected by the dynamical behavior of the orientation. Shear banding is an example of the remarkable non-Newtonian feedback that is possible in such systems. For colloidal rods with a permanent electric (magnetic) dipole moment additional exciting effects are expected. The calculations presented here are based on a self-consistent hydrodynamic model including feedback effects between orientational motion and velocity profile [1]. The competition between shear-induced tumbling motion (observed in colloidal suspensions of rod-like fd virus [2]) and the boundary conditions imposed by plates leads to oscillatory alignment structures. These give rise to a spontaneous time-dependent polarization and to oscillating local spurts of the velocity profile [3]. Moreover, our model can be extended to polar active biomaterials by including ``activity terms''. Finally, some preliminary results of the local spurt effect in active polar colloidal suspensions are presented. [1] S. Grandner, S. Heidenreich, S. Hess and S. H. L. Klapp, EPJE 24, 353 (2007).; M. G. Forest, S. Heidenreich, S. Hess, X. Yang and R. Zhou JNNFM 155, 130 (2008). [2] M. P. Lettinga, Z. Dogic, H. Wang, J. Vermant, Langmuir 21, 8048 (2005). [3] S. Heidenreich, S. Hess, and S. H. L. Klapp, submitted to PRL.