VISCOUS DISSIPATION RATE IN CONCENTRATED SUSPENSIONS

The constitutive equation proposed by Phillips et al. [Phys. Fluids A 4, 30 (1992)] for shear induced particle migration in viscous flows of concentrated suspensions is used to calculate the change in viscous d issipation rate occurring when the particle distribution changes from a homogeneous state to the steady state. Four cases of simple unidirec tional flows are considered. Two of these cases were discussed by Phil lips et al. and are revisited here. In all cases, the expected decreas e in the dissipation rate is found to be considerable. The degree of r eduction in dissipation rate is influenced by whether the shear-induce d migration is parallel or normal to the velocity gradient.