The use of Computational Fluid Dynamics to Determine the Dynamic Stability of an Autonomous Underwater Vehicle

Various forms of Autonomous Underwater Vehicles (AUVs) have evolved to solve different subsea mission requirements, these can be loosely grouped into two types: torpedo style AUVs and hovering AUVs. Torpedo AUVs were initially developed to be launched from torpedo tubes and consequently resemble torpedoes with a propeller and control surfaces at the rear, these vehicles have poor slow speed maneuverability due to inefficiency of the control surfaces at low speed, but have good straight line performance due to their streamlined shape. AUVs of this type are predominantly used for pipeline inspection, environmental monitoring, scientific research and other long range applications. Hovering AUVs tend to be used for applications where a greater level of slow speed maneuverability is required. These vehicle use a number of thrusters to maintain depth and heading control. The eventual aim of the program of work under way is to develop specific AUV hull concept design techniques that are robust and reliable. To this end, Computational Fluid Dynamics (CFD) analysis methods are being investigated which combine automated meshing and parametric hull shape definitions to reduce overheads when evaluating the design of a concept AUV hull. Since each AUV application requires varying levels of dynamic stability and maneuverability this work uses steady state CFD analysis to determine numerically the dynamic stability of an AUV. In order to verify the methodology the procedure has been performed for the torpedo style AUV Autosub, (see Fig 1), for which there is suitable experimental data to benchmark the solutions.