Numerical underwater radiated noise prediction in multi-phase flow conditions

The results of a mesh sensitivity study for hydroacoustic simulations of a NACA 662−415 section elliptic wing in cavitating conditions are presented. The results of flow field and acoustic field analyses were compared using two distinct methodologies for the acoustic examination: the fully impermeable approach and the fully permeable approach. From the flow field analysis, a quadratic convergence for both lift and drag was obtained with numerical uncertainties below 2.5% for all cases. The deviation from the experiment found for the lift was below 6%. For the acoustic results, the impermeable approach exhibited robust convergence for all noise terms, with p values ranging from 1 to 3 and numerical uncertainties below 6% for all noise source terms and below 1.5% for the global noise term. However, for the permeable approach, the convergence of surface terms notably increased due to the amplification of the noise signal amplitude. Nevertheless, although this had an impact on the uncertainties of the global noise term, the convergence remained acceptable. Overall, the flow and acoustic results were consistent, and the noise comparison with the experiments was satisfactory.