Computational Approaches for the Prediction of Hull Pressure Fluctuations

A conventional propeller-hull configuration in operating conditions is considered for the prediction of the pres- sure disturbance on the hull surface. The problem is studied in a multidisciplinary context involving propel- ler hydrodynamics, propeller hydroacoustics and hull- acoustics scattering. An unsteady approach for inviscid flows based on a Boundary Element Method (BEM), including cavitation modelling, is applied to describe the hydrodynamics features of a propeller-hull configu- ration; since the mutual interaction between propeller and hull is described by a time-accurate approach, this method is referred to as interactional hydrodynamics. As hydroacoustics solver, the Ffowcs Williams and Hawkings Equation (FWHE) is applied accounting for the effects induced by the dynamic of sheet cavitation phenomena (if present) occurring upon the blades sur- face. The emphasis of the work is on theoretical and computational aspects concerning the evaluation of the acoustics scattering from the hull-surface when it is impinged by the pressure waves coming from the pro- peller. To this aim, the interactional approach, coupled to the Bernoulli theorem, is compared to a novel scatter- ing model based on a nonstandard application of FWHE. Potentialities and drawbacks of the above mod- elling are discussed both theoretically and numerically.