Numerical study of the motion of a self-propelled dumbbell in fluids

The fluid mechanics of micro swimmers at low Reynolds number has attracted considerable attention due to its potential of biomedical applications. For a dumbbell (i.e., a swimmer formed by two balls of different sizes), the effects of asymmetric shape and inertia makes it moving in Newtonian fluids when rotating about its axis of symmetry at finite Reynolds number. This dumbbell moves in the direction of its axis of symmetry with the larger ball ahead. In this talk, we study its propulsion in different configurations computationally at low Reynolds number regime and obtain some quasi-optimal configurations. But, for such rotating asymmetric dumbbell in an Oldroyd-B fluid at the Stokes regime, numerical and experimental works showed that it moves with the small ball ahead. The competition between the inertia and elastic forces is studied at low Reynolds number for such dumbbell swimming in Oldroyd-B fluids.