Numerical simulation of viscous flows about underwater vehicles

The present study was undertaken to provide information for both design improvement and control system development during various stages of an autonomous underwater vehicle (AUV) development project. The need to establish a predictive capability for the hydrodynamic (control) coefficients for an AUV presented an opportunity to apply a multiblock incompressible Navier-Stokes flow solver which has evolved over many years. The solver utilizes a state-of-the-art implicit, upwind numerical scheme to solve the time-dependent Navier-Stokes equations in a generalized time-dependent curvilinear coordinate system. Domain decomposition is accomplished via a general unstructured multiblock approach. Numerous simulations were conducted during the course of this work. The computations for vehicle and propulsor design consisted mainly of steady state axisymmetric computations, while for control system development both steady and unsteady (prescribed motion) simulations were conducted. The latter cases focus on the forces and moments on the vehicle that are needed for extraction of control information. A brief overview will be presented on the flow solver. This will be followed by a presentation of the numerical results.