Two-link swimming using buoyant orientation

The scallop theorem posits that a two-link system immersed in a fluid at low Reynolds number cannot achieve any net translation via cyclic changes in its hinge angle. Here, we propose an approach to “breaking” this theorem, based on a static separation between the centers of mass and buoyancy in a net neutrally buoyant system. This separation gives the system a natural equilibrium orientation, allowing it to passively reorient without changing shape. © 2010 American Institute of Physics. doi:10.1063/1.3481785