Three-dimensional evolution of body and fluid motion near a wall

Abstract

Evolution of three-dimensional body motion within surrounding three-dimensional fluid motion is addressed, each motion affecting the other significantly in a dynamic fluid–body interaction. This unsteady problem is set near a wall. The spatial three-dimensionality present is a new feature. For inviscid incompressible fluid, a basic nonlinear formulation is described, followed by a linearised form as a first exploration of parameter space and solution responses. The problem reduces to solving Poisson’s equation within the underbody planform, subject to mixed boundary conditions and to coupling with integral equations. Numerical and analytical properties show dependence mainly on the normal and pitch motions, as well as instability or bounded oscillations depending on the position of the centre of mass of the body, and a variety of three-dimensional shapes is examined.