Underwater jet noise simulation based on a Large-Eddy Simulation/Lighthill hybrid method

Abstract

In recent years, extensive research about the numerical method for aeroacoustics simulation has been made available. However, the research on hydrodynamic noise has been slow to develop. In this paper, a hybrid method of combining Large-Eddy Simulation (LES) and Lighthill's acoustic analogy theory is established to compute the hydrodynamic noise, which is based on a method for aerodynamic noise prediction under low Mach number. First, a model of a three-dimensional underwater jet is built according to an experimental model, while the Computational Fluid Dynamics (CFD) mesh and the acoustic mesh are both prepared. Then, the flow field of underwater jet is simulated with LES. The characteristics of turbulent flow are analyzed by the pressure difference and the uniformity coefficient of velocity. After that, the noise of underwater jet is simulated using the theory of Lighthill's acoustic analogy. Finally, the solutions obtained by the hybrid method are compared with the experimental data available in open research. In conclusion, the trend of the sound pressure level versus the frequency at the observation point agrees consistently with the experimental data. The LES/Lighthill hybrid method is able to predict the underwater jet noise or hydrodynamic noise.