Quasi-static analysis of the hydrodynamic interaction effects on an autonomous underwater vehicle operating in proximity to a moving submarine

When an Autonomous Underwater Vehicle (AUV) operates close to a submarine, interaction with the flow and pressure fields of the submarine can adversely affect the motion of the AUV. These interactions can result in uncontrollable motions of the AUV, which in extreme cases can lead to mission failure due to collision with the submarine or the inability of the AUV to maintain the desired trajectory. This paper outlines the steady-state interaction forces and moments acting on the AUV at different fixed speeds and relative positions to the submarine, with an aim to identify the regions where adverse effects due to interaction are minimal. The results presented in this paper are from a series of model scale and full scale Computational Fluid Dynamics (CFD) simulations on axisymmetric AUV and submarine models at diameter ratios between the two vehicles models of 2.239, 5.723 and 14.634. Validation was carried out for the lower diameter ratio at model scale using captive model experiments. Results show that the adverse effects of the interaction forces and moments were minimal when the AUV׳s centre of buoyancy is around amidships of the submarine, providing a relatively safe operating path for the AUV.