  We experimentally study the flow past a rigid plate with an attached closed
filament acting as a deformable afterbody in the soap film. The complex
fluid-structure interactions due to its deformable shape and corresponding
dynamics are studied. We find the shape of the afterbody is determined by the
filament length and flow velocity. A significant drag reduction of up to 9.0%
is achieved by adjusting the filament length. We analyze the drag mechanism by
characterizing the deformable afterbody shape and wake properties. Our
experiment and modeling suggest that such favorable flow control and drag
reduction are expected to occur over a specific flow speed regime when the
flexible afterbody is suitably added.
