The hydrodynamic interaction effects on a fully appended AUV operating near a moving submarine

When an Autonomous Underwater Vehicle (AUV) is operating in close proximity to a moving submarine, the hydrodynamic interaction between the two vehicles can prevent the AUV from maintaining its desired trajectory, which in extreme cases can lead to collision or mission failure. Designers and operators need to have a good understanding of the hydrodynamic interaction between the two vehicles in order to develop adequate and robust AUV control systems to ensure vehicle stability and identify operating parameters in which the AUV can effectively and safely manoeuvre near the submarine. Previous work by the authors identified the effects of the hydrodynamic interaction forces and moments acting on the AUV operating near a moving submarine, with both vehicles represented by axisymmetrical hull forms. This study extends it to include the effects of the AUV aft control surfaces, identifying their effects on the interaction behaviour. The results presented are from a series of Computational Fluid Dynamics (CFD) simulations on axisymmetric and appended AUV and submarine hull forms, with validation of the CFD model carried out through scaled captive model experiments. The results show that the addition of appendages to the vehicles have substantial effect on the interaction behaviour, in particular the interaction-induced side forces and turning moments on the AUV. This work on appended AUVs extends our understanding of AUV behaviour and interaction, enabling the prediction and safe strategies for manoeuvres when operating around a moving submarine.