Prediction of chain length effects in elongational flows of dilute polymer solutions by successive fine graining

A new computational tool for predicting the rheological properties of a dilute solution of polymers in ?-conditions is presented. Within this approach, the polymer is modelled as a bead spring chain with finitely extensible springs and fluctuating hydrodynamic interactions incorporated. The novelty of the method lies in obtaining predictions for a very large Kuhn step chain by extrapolating results of a series of bead-springs representations to the bead-rod limit. This provides the computational advantage of using smaller number of modes in a coarse grained description and better accuracy in the extrapolated result. The effect of chain length in the unraveling dynamics of a polymer in elongational flow is examined using this approach