Nonlinear dumbbell model for flexible polymers: dynamical phenomena

We study the stress growth upon the inception of steady shear and steady elongational flow for a nonlinear dumbbell model for flexible macromolecules suspended in a Newtonian fluid. The internal force law is made nonlinear by adding a cubic term to the Hookean force law. The generalization to a nonlinear chainlike bead—spring model is outlined. In order to consider higher concentration effects also the configuration-dependent tensorial mobility is included. We use the mean-field approximation and test this approximation with a Brownian dynamics simulation. The mean-field results for the material functions are compared with experimental results for both flow situations.