Floppy fluid vesicles in elongational flow

The behavior of self-avoiding fluid vesicles in elongational flow is studied using Monte Carlo simulations and scaling arguments. The simulations are carried out for membranes with a very small bending rigidity, in the free-draining approximation. We find that there is a gradual crossover from self-avoiding branched-polymer to elongated linear-polymer behavior as the flow rate is increased. At small flow rates, our results scale with the relaxation time of undisturbed branched polymers. The scaling behavior is the same in both unidirectional and planar flow geometries.