Free running simulation of an Autonomous Underwater Vehicle undergoing a straight line manoeuvre via computational fluid dynamics

This paper presents the initial development towards the modelling of a free running simulation to examine the manoeuvring performance of self-propelled underwater vehicles. The simulation consists of a coupled Computational Fluid Dynamics (CFD) and Rigid Body Dynamics (RBD) model that enables the prediction of the vehicle’s hydrodynamic characteristics and trajectory. It uses a Moving Domain Technique (MDT) that overcomes grid deformation and boundary limitation issues. The CFD model was validated against Experimental Fluid Dynamics (EFD) data for a prolate spheroid and a generic bare hull (SUBOFF), with the coupled model verified for the two hulls by undergoing straight line manoeuvres. An actuator disk propeller was then added to a fully appended SUBOFF model to simulate a 1-DOF self-propelled free running vehicle. Future work is in progress to expand the capability of the model for 6-DOF manoeuvring simulations. The model is intended as a cost effective tool to complement free running experimental work, hence reducing the reliance on specialised experimental equipment and providing a tool that can predict manoeuvring conditions beyond experimental limitations.