  Improved designs for Autonomous Underwater Vehicles (AUV) are becoming
increasingly important due to their utility in academic and industrial
applications. However, a majority of such testing and design is carried out
under conditions that may not reflect the operating environment of shallow
water AUVs. This may lead to imprecise estimations of the AUV's performance and
sub-optimal designs. This article presents experimental and numerical studies
carried out in conjunction, to investigate the hydrodynamic characteristics of
AUV hulls at different Reynolds numbers over sloped channel-beds. We carry out
experiments to measure the velocity field and turbulent statistics around the
AUV with quantified uncertainty. These are contrasted against corresponding
flat bed experiments to gauge the effect of test bed topography on AUV
performance. The experimental data was used to validate Reynolds Stress Model
predictions. Hydrodynamic parameters such as drag, pressure and skin friction
coefficients were predicted from the RSM simulations at different test bed
slopes, angles of attack and drift angles of the AUV hull, to analyze the
hydrodynamic performance of the AUV. The results presented in this article
offer avenues for design improvement of AUVs operating in shallow environments,
such as the continental slope and estuaries.
