Configuration-Dependent Hydrodynamics Interaction in Flows of Dilute Polymer Solutions.

We have extended the bead-spring model of Zimm to include hydrodynamic interaction that depends upon the conformation of the polymer and hence the deformation rate. Our computational scheme is based on the method of Fixman, and it allows us to investigate numerically chains as large as 500 beads. The major approximation is replacement of the hydrodynamic interaction tensor with its configurational average. We find that the incorporation of configuration-dependent hydrodynamic interaction qualitatively changes the Zimm predictions for both the shear and the elongational viscosity. In particular, the elongational viscosity becomes a multi-valued function of the rate of elongation. This result is consistent with the coil-to-stretch transition predicted by de Gennes and Hinch.