Numerical Investigation of Hydrodynamic Performance of an AUV Moving near the Bottom Wall

Autonomous underwater vehicles (AUVs) are widely employed in missions conducted near the seabed, including underwater inspection, seabed mapping, and marine resource exploration. During such operating conditions, the interaction between the AUV and the bottom wall can significantly influence the surrounding flow field and the hydrodynamic characteristics of the vehicle. In this study, a numerical investigation is carried out to examine the influence of near-bottom effects on the hydrodynamic performance of an AUV using a commercial Computational Fluid Dynamics (CFD) solver. The seabed is assumed as a flat wall, and two operating conditions are considered, including an open-water case and a near-bottom case with a clearance ratio of h/LA = 1.93. The flow field is investigated through analyses of hydrodynamic force, pressure distribution, and wake structures. The results indicate that the wall bottom noticeably alters the pressure field and wake development around the AUV, leading to changes in total resistance and flow separation. The findings provide useful insights into the hydrodynamic mechanisms associated with near-bottom operation and offer valuable guidance for the design, control, and operation of AUVs performing missions in shallow or seabed-related missions.