Hydrodynamic and hydroelastic analyses of a plate excited by the turbulent boundary layer

Recent studies have demonstrated that the characterisation of wall-pressure fluctuations for surface ships is of great interest not only for military applications but also for civil marine vehicles. A ship model towed in a towing tank is used to perform pressure and structural measurements at high Reynolds numbers. This facility provides ideal flow conditions because background turbulence and noise are almost absent. Free surface effects are naturally included in the analysis, although in the particular section chosen for the present study do not have significant consequences on pressure spectra. Scaling laws for the power spectral density are identified providing the possibility to estimate pressure spectra for different flow conditions and in particular for full-scale applications. The range of validity of some theoretical models for the cross-spectral density representation is analysed by direct comparison with experimental data of wall-pressure fluctuations measured in streamwise and spanwise direction. In a second phase, an indirect validation is performed by comparing the measured vibrational response of an elastic plate inserted in the catamaran hull with that obtained numerically using, as a forcing function, the modelled pressure load. In general, marine structures are able to accept energy mainly from the sub-convective components of the pressure field because the typical bending wavenumber values are usually lower than the convective one; thus, a model that gives an accurate description of the phenomenon at low wavenumbers is needed. In this work, it is shown that the use of the Chase model for the description of the pressure field provides a satisfactory agreement between the numerical and the experimental response of the hull plate. These experimental data, although acquired at model scale, represent a significant test case also for the real ship problem.