Non-Newtonian rotational swimming: experiments

Recently Pak et al. (PoF, 2012) showed that a device composed of two unequal spheres (snowman) could swim in a viscoelastic fluid under a rotational actuation. By symmetry such device isn't able to move in a Newtonian fluid but because of its geometrical asymmetry is able to generate asymmetric elastic response and generate a purely viscoelastic thrust. We implemented this swimmer experimentally using a magnetic snowman driven by an external rotating magnetic field. We demonstrate that the snowman swims solely as a result of fluid elasticity. We conduct tests in Newtonian and Boger fluids, varying the sphere size ratio and rotation speed. We also conducted measurements in a confined environment, which showed an improved swimming performance.