  This article presents experimental and numerical studies on the effect of
free stream turbulence 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.
