Numerical Simulation of Steady and Unsteady Motion for an AUV with Complex Geometry

Abstract This article simulates steady and unsteady motion of a complex geometry AUV (Autonomous Underwater Vehicle) pumped by four stern tubes. The model is similar to actual body without any simplification in order to get high resolution result, meshed by hybrid grids with prismatic grids near body while unstructured grids filling the left domain. Integrating to RNG k-e equation by cell centered finite volume scheme, the steady resistance is got and compared with that of experiment. Dealing with this analytical data we correct the experiment data, within 1.7 percent difference. During unsteady motion, added moment source is added to moment equation, while implicit dual time is applied to discretize the time dependent conserved variables, the complex pump-propelled AUV moving from stationary to a constant velocity (steady velocity) is simulated, with acceleration dicreasing in exponential with time. Its drag and corresponding velocity vector are obtained at each time step. The drag at constant velocity is validated compared with that of steady motion.