Cavitation underwater radiated noise methodology applied to a propeller operating in-behind condition

Concerns about shipping noise influence on marine life are motivating mitigation efforts, increasing interest in numerical methods for underwater radiated noise (URN) assessment. A common approach is to use incompressible flow solvers with the Ffowcs Williams-Hawkings (FW-H) method, though reliability is shown to depend on modelling choices. To advance on this matter, model and full scale simulations are performed for a fully appended ship, operating in mildly cavitating conditions, using the incompressible Reynolds-averaged Navier–Stokes (RANS) framework to investigate pressure pulse and URN levels. Predictions are compared with model scale experiments and full scale sea trial measurements. The permeable FW-H method is used, while also an alternative approach modelling cavitation as a monopole source combined with the solid FW-H formulation and corrections for Lloyd’s mirror effect is proposed and tested. Further, the effect of blockage on cavitation is investigated and found to affect induced pressure pulse and URN levels due to effects on the ship wakefield in the tunnel section. Although good agreement is found for cavity dynamics and pressure pulses, significant discrepancies are found in URN levels between measurements and numerical predictions, for both methods. Reasons for these differences are partly understood and discussed, while other questions remain open.