Understanding the hydrodynamic coefficients of Autonomous Underwater Vehicles is vital for predicting their dynamic and control behavior. The aim of the present study is to determine the hydrodynamic coefficients of a research AUV developed in the I.U.T Subsea C D Center, using Computational and Experimental Fluid Dynamics methods. Experimental studies in the present study Includes; design and manufacturing of a 1:1 scaled model of the AUV and test the model in the I.U.T towing tank. Tests considered in this study are carried out for two general cases: with and without angle of attack, in the Reynolds range of . In these experiments, AUV is connected to the carriage by two Struts. In order to investigate the effect of depth of the AUV submergence, on the obtained results, tests were conducted at two different depths, namely 40 and 60 cm. To study the effect of the strut, both cylindrical and NACA0012 Struts have been used. The obtained results showed that, because of reducing the effects of free surface and wave resistance, the drag force decreases with increasing the AUV submergence depth. On the other hand, the drag force might increases with depth because in this case, there is more time for the resulting vortex to grow. The experiments showed that, while, at the depth of 40 cm, using the cylindrical and NACA0012 Struts, resulted in the same net drag force, at the depth of 60 cm, there are some discrepancies in the resulting drag forces. This is due to the vibration of the struts (resonance), when they are tested alone at the speeds higher than1.75 meters per second. The effect of control surfaces on the obtained results is also investigated. All the experiments carried out in the towing tank, were also, simulated by ANSYS CFX code. The results of the two methods are compared. To obtain the hydrodynamic coefficients related to the added mass, the motions produced by a planar motions mechanism (PMM) were also simulated by ANSYS CFX. The simulated motions include: surge, pure sway and pure yaw. Mesh deformation are used to imulated the required oscillatory motions. Key Words: Hydrodynamic coefficients, Experimental fluid dynamics, Computational fluid dynamics, Towing tank , Planar motion mechanism , Mesh deformation.
