ON THE MOTION OF A NONRIGID SPHERE IN A PERFECT FLUID

We consider in the paper the problem of the motion of a slightly deformable sphere embedded in a non-uniform potential flow-field. It is demonstrated that up to the first-order in the surface-deformation amplitude, the equations for the linear and angular velocities are uncoupled. After deriving the dynamic equations by accounting for the small surface deformations, we treat the phenomenon of the body's self-propulsion and point out to a qualitative difference between the self-propulsion of a deformable sphere in a quiescent or uniform surrounding and, that in a non-uniform ambient flow-field. The effect is more significant (by an order of magnitude) in the latter case. Also discussed is the corresponding parametric resonant interaction as a possible mechanism for self-propulsion.