Dynamics of rigid and flexible extended bodies in viscous films and membranes.

We study the dynamics of extended rodlike bodies in (or associated with) membranes and films. We demonstrate a striking difference between the mobilities in films and bulk fluids, even when the dissipation is dominated by the fluid stress: For large inclusions, we find that rotation and motion perpendicular to the rod axis exhibit purely local drag, in which the drag coefficient is algebraic in the rod dimensions. We also study the dynamics of the internal modes of a semiflexible inclusion and find two dynamical regimes in the relaxation spectrum.