Finite difference solutions of compressible viscous fluid flows over pitching bluff bodies

Abstract

Box-shaped containers when carried by cable harness from helicopters are known to have complicated motions, in many degrees of freedom and with varying degrees of stability. The resulting motions are caused by the complex aerodynamics of, for example, unsteady movements of the containers. These motions create, and are in turn sustained by, complex aerodynamic flows and forces.Steady forward motion of the container results in separation bubbles initiating from the container leading edges. Sometimes the separating stream surfaces will re-attach to the container surface at some station downstream from the leading edges. In other cases, no reattachment occurs and the container is considered to be in the ‘wake’ of the forward facing surface.Unsteadiness in the fluid motion, when induced most importantly, for example, by the pitching of the container, can significantly alter the criteria governing the formation of the separating stream surface and its re-attachment.