Hydrodynamic interaction facilitates the unsteady transport of two neighboring vesicles.

We obtain a numerical solution of the equation for the synchronous unsteady motion of two spherical vesicles in incompressible viscous fluid in the presence of both Stokes drag and hydrodynamics memory. We find that for a given amount of work performed, the final distance traveled by each vesicle is increased by the presence of the other vesicle moving in the same direction. The result suggests that the unsteady transport of the vesicles by molecular motors in vivo may be facilitated due to an effective hydrodynamic interaction between the neighboring vesicles.