Large eddy simulation of turbulent wake flow around a marine propeller under the influence of incident waves

Abstract

In practical applications, propellers often operate beneath incident waves. To investigate the effects of waves on turbulent propeller wakes, a comparative study of the instantaneous flow fields and turbulent statistics of propeller wakes under open-water condition and with incident waves is conducted through the large-eddy simulation framework. The simulations are performed on a Cartesian grid, with the air–water interface captured using a coupled level-set and volume-of-fluid method. The complex geometry of the propeller is captured using an immersed boundary method. The results show that, near the water surface, the existence of incident waves accelerates the wake flow in the axial direction. Both the mean axial velocity and turbulent kinetic energy exhibit phase-lag behavior in the presence of incident waves. Waves increase the instability of the flow in the far-wake region, resulting in the rising of turbulent kinetic energy. Further analysis of the power spectral density shows that the velocity fluctuations gain energy from the waves at low frequencies, and nonlinear interactions between wave-induced motion and turbulent fluctuations transport energy from low to high frequencies as the wake flows downstream. The present study shows the potential of the large-eddy simulation framework to provide engineering guidance and a theoretical basis for the design and operation of propellers in wave environments.