Dynamics of interacting vesicles and rheology of vesicle suspension in shear flow

We studied the dynamics of isolated vesicles as well as vesicle interactions in semidilute vesicle suspensions subjected to a shear flow. We found that the long-range hydrodynamic interactions between vesicles give rise to strong fluctuations of vesicle shape and inclination angle, empty set, though the functional dependence of empty set and the transition path to tumbling motion is preserved. The dependence of the suspension viscosity on the viscosity ratio between inner and outer fluids, lambda, was found to be non-monotonic and surprisingly growing with lambda at the fixed outer fluid viscosity for lambda < 1, at odds with recent predictions made for a dilute suspension of non-interacting vesicles. Copyright (c) EPLA, 2008.