The Effect of the Hydrodynamic Interaction on the Rheological Properties of Hookean Dumbbell Suspensions in Steady State Shear Flow

The diffusion equation for the configurational distribution function of Hookean dumbbell suspensions with the hydrodynamic interaction(HI) was solved, in terms of Galerkin's method, in steady state shear flow;and viscosity,first and second normal-stress coefficients and molecular stretching were then calculated. The results indicate that the HI included in a microscopic model of molecules gives rise to a significant effect on the macroscopic properties of Hookean dumbbell suspensions. For example, the viscosity and the first normal stress coefficient, decreasing as shear rate increases, are no longer constant;the second normal-stress coefficient, being negative with small absolute value and shear-rate dependent, is no longer zero;and an additional stretching of dumbbells is yielded by the HI. The viscosity function and the first normal-stress coefficient calculated from this method are in agreement with those predicted from the self-consistent average method qualitatively, while the negative second normal-stress coefficient from the former seems to be more reasonable than the positive one from the latter.