Abstract

The aim is to develop computational techniques for studying aerodynamic interactions between multiple objects when an object exits and separates from an aircraft. The object could be a paratrooper jumping out of a transport aircraft or a package of emergency aid dropped from a cargo plane. In all these cases, the computational challenge is to predict the dynamic behavior and path of the object, so that the separation process is safe and effective. This is a very complex problem because it has an unsteady, 3D nature and requires the solution of complex equations that govern the fluid dynamics of the object and the aircraft together, with their relative positions changing in time. In advection-dominated flows, the numerical boundary layer is excessively thick and not physically real. Computational methods used to solve such problems much address this as a numerically thick boundary layer can artificially affect the dynamics and trajectory of moving objects. In the presented research, numerically thick boundary layers were reduced for 3D flows specifically focusing on paratrooper-aircraft separation. Slip formulations were found to provide an excellent numerical approximation of a thin boundary layer for this application. A real paratrooper trajectory was numerically simulated.

Key words: Mesh resolution, boundary layer, mesh generation, boundary layer resolution, boundary layer elements, slip conditions, Navier-stokes equation, incompressible flow.