NUMERICAL VALIDATION OF THE HYDRODYNAMIC DRAG OF A SURFACED AND FULLY APPENDED UNDERWATER VEHICLE

Underwater Vehicles (UV) are required to travel on the surface for periods of time to complete mission requirements. However, knowledge on the drag of a surfaced UV is scarce in the public domain and the knowledge on the behaviour of surface craft is generally not applicable due to substantial differences in hull form. This paper presents a numerical study on the drag coefficient of a surfaced and fully appended BB2 UV in calm water. The results were firstly validated with the available experimental drag data for a range of speeds. Secondly, the free surface elevation along the length of the UV photographed during physical model scale experiments is compared to the free surface elevation predicted by CFD. This research has shown that a multiphase CFD model can accurately predict the drag due to the forward motion of a surfaced UV in calm water.