ETH Polymer Physics seminar


2012-11-28
10:15 at HCI J 574

Mesoscale Hydrodynamic Simulation of Polymers in Flow Fields

Roland Winkler

Polymer Physics, Department of Materials, ETH Zurich

Experimental studies of individual DNA molecules in steady shear flow by fluorescence microscopy have provided a wealth of information on single polymer dynamics. In particular, these experiments reveal remarkably large conformational changes due to tumbling motion; i.e., a polymer stretches and recoils in the coarse of time. Since shear flows are omnipresent in biological systems and technical applications, e.g., microfluidics, the understanding of the dynamics of semiflexible polymer---such as DNA---is of great practical interest. The microscopic conformational properties affect the macroscopic rheological behavior of the polymer solution, and hence a detailed theoretical description of the microscopic dynamics is desirable. The dynamic behavior of a macromolecule in shear flow is governed by various parameters; aside from the shear rate, the finite chain extensibility is of major importance. The the talk, the significance of hydrodynamic interactions on the dynamics of dsDNA molecules in solution will be discussed based on an analytical model for semiflexible polymers. In addition, the dynamics of semiflexible polymers under the influence of shear flow is studied. Power laws are derived for various conformational and dynamical quantities which are in agreement with experimental findings. In particular, the tumbling motion is analyzed. The calculations explain the similarities in the behavior of flexible and semiflexible polymers as well as free-draining and non-draining systems.


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