Euler-Lagrange study on the bubble wake of a ship with waterjet propulsion

The physics of the breaking waves and bubble wake of a waterjet propelled ship are numerically studied. A hybrid Euler-Lagrange method is proposed to investigate the underlying mechanism of the bubble behaviors in the turbulent wake. The adaptive mesh strategy is adopted to capture the large deformed free surface with Detached Eddy Simulations (DES). Discrete droplets or bubbles are detected according to the transition criterion based on the volume fraction of the grid unit. Behaviors of multi-scale droplets/bubbles are simulated with the introduction of the breakup model. The mechanisms of air entrainment caused by the impacting jet are better understood with the analysis of the bubble generation, transport, size distribution and secondary breakup in the ship wake. A strong correlation is observed between the turbulent intensity and the bubble transportation. The visual visibility of the waterjet ship's wake depends more on the retention characteristics of small-diameter bubbles near free surface. The current approach provides an effective way to simulate the cross-scale complex flow without increasing the grid number greatly.