The effects of free stream turbulence on the hydrodynamic characteristics of an AUV hull form

Abstract This article presents experimental and numerical studies on the effect of free stream turbulence (FST) on evolution of flow over an autonomous underwater vehicle (AUV) hull form at three Reynolds numbers with different submergence depths and angles of attack. The experiments were conducted in a recirculating water tank and the instantaneous velocity profiles were recorded along the AUV using Acoustic Doppler Velocimetry (ADV). The experimental results of stream-wise mean velocity, turbulent kinetic energy (TKE) and Reynolds stresses were used to validate the predictive capability of a Reynolds stress model (RSM) with the wall reflection term of the pressure strain correlation. From the high fidelity RSM based simulations it is observed that in presence of free stream turbulence, the pressure, skin friction, drag and lift coefficients decrease on the AUV hull. The variation of the hydrodynamic coefficients were also plotted along the AUV hull for different values of submergence depth and angle of attack with different levels of free stream turbulence. The conclusions from this experimental and numerical investigation give guidance for improved design paradigms for the design of AUVs.