Modelling out-of-plane hydrodynamic hysteresis in horizontal submarine maneuvers with indicial responses

• Unsteady maneuvers for the BB2 submarine have been simulated with CFD. • Simulation results are validated with experimental force and pressure measurements. • CFD simulations are used to develop an indicial response model. • Hysteresis effects are shown to severely impact the out-of-plane hydrodynamics. • The performance of the ROM is improved substantially by including history effects. Predicting the transient hydrodynamic loads in submarine maneuvering simulations has traditionally been limited to quasi-steady modelling assumptions which are not well-founded in extreme maneuvering scenarios. Recent studies have shown that the time-history of the wake is significant for the out-of-plane hydrodynamics of a submarine in horizontal maneuvers. Despite efforts of modelling these effects with integral-type impulse response methods, known within the vehicle dynamics community as indicial theory, the complex separation and development of the wake surrounding the hull causes significant modelling errors in high frequency oscillation maneuvers. This study investigates characteristics of the time-domain hydrodynamic response of an SSK-class submarine, and a corresponding reduced-order model implementation. Model predictions for a set of small and large amplitude drift oscillation maneuvers are used to demonstrate the shortcomings of the current model formulation. A revised model designed to modify the high-frequency response of the vehicle is shown to significantly improve the qualitative and quantitative performances of the model in large amplitude oscillations.