Hydrodynamic parameter estimation of DARPA SUBOFF using dynamic pitch maneuver

The DARPA SUBOFF model is widely used for studying underwater vehicle performance, and many researchers have explored its behavior through experiments and simulations. The hydrodynamic flow over the underwater vehicle and its appendages during dynamic pitch maneuver is complex. Therefore, it necessitates conducting detailed flow analysis of boundary layer attachment and detachment while in a dynamic state. For this purpose, this study presents detailed insight on dynamic maneuver to capture the complete flow profile, flow field parameters, hydrodynamic effects, and vortex shedding behind stern appendages. In the present study, the transient maneuvering of the DARPA SUBOFF with respect to the lateral axis was carried out at multiple angles of attack from − 30 to + 30° while the sterns were deflected with an increment of 5° ranging from − 30 to 30°, and the data was recorded. This rotation of control surfaces actuated by 5° increment ranging from − 30 to + 30° provided 13 different simulations for actuation cases on which the dynamic pitch maneuver was carried out. However, literature shows most of these studies have focused on fixed control surfaces and only a few selected angles of attack (AoA). The hydrodynamic coefficients such as drag (C_d), lift (C_L), and and moment (C_m) are calculated for different pitching angles at a speed of 3.05 m/s. The results are first validated at zero AoA and then compared across various control surface angles. The coefficients showed consistent and systematic trends during the pitching motion, with C_d ranging from 0.02 to 0.025, C_L from − 0.04 to 0.042, and C_m from − 0.015 to 0.012. This study provides more detailed insights into the dynamic behavior of underwater vehicles, which is important for improving their control and stability.