DYNAMIC EQUATIONS OF MOTION FOR A RIGID OR DEFORMABLE BODY IN AN ARBITRARY NONUNIFORM POTENTIAL FLOW-FIELD

In this paper we present a general method for calculating the hydrodyn amic loads (forces and moments) acting on a deformable body moving wit h six degrees of freedom in a non-uniform ambient potential flow field . The corresponding expressions for the force and moment are given in a moving (body-fixed) coordinate system. The newly derived system of n onlinear differential equations of motion is shown to possess an impor tant antisymmetry property. As a consequence of this special property, it is demonstrated that the motion of a rigid body embedded into a st ationary flow field always renders a first integral. In a similar mann er, we show that the motion of a deformable body in the presence of an arbitrary ambient flow field is Hamiltonian. A few practical applicat ions of the proposed formulation for quadratic shapes and for weakly n on-uniform external fields are presented. Also discussed is the self-p ropulsion mechanism of a deformable body moving in a non-uniform stati onary flow field. It leads to a new parametric resonance phenomenon.