  In this article, the hydrodynamic characteristics of Autonomous Underwater
Vehicles (AUVs) are investigated and analyzed under the influence of rotating
flow fields, that were generated in a recirculating water tank via a rotating
propeller. Initially, experiments were carried out for the measurement of flow
field variables and Quantities of Interest across the AUV in the presence of
the rotating propeller while varying the rotational speed and the extent of
rotational flow strength. The flow field across the AUV was measured using an
Acoustic Doppler Velocimeter (ADV). These measured turbulent flow statistics
were used to validate the Reynolds Stress Model (RSM) based numerical
predictions in a commercial CFD solver. After preliminary validation of the
turbulent flow statistics with the numerical predictions, a series of numerical
simulations were performed to investigate the effect of the rotational flow
field of the propeller on the drag, skin friction and pressure coefficients of
the AUV. The operating speed and location of the propeller were also varied to
check their affects on the hydrodynamic performance of AUV. The results
provided in this article will be useful for the design optimization of AUVs
cruising in shallow water where the flow is highly rotational because of
wave-current interactions. Additionally the results and analysis are relevant
to study the design and operation of AUVs that have to operate in a group of
unmanned underwater vehicles or near submarines and ships where the flow field
is highly complex and such rotational effects are present.
