Wake and air entrainment properties of transom stern over a wide range of Froude numbers

In the present study, high-fidelity simulations of the wake behind a transom stern are performed with a block-based adaptive mesh refinement technology. By transom stern, we mean a square-ended stern of a ship, which is a favorable design for the high-speed ship. The sharp volume of fluid method is adopted to capture the gas-liquid interface, and the immersed boundary method is applied to simulate the boundaries of ship hull. Simulation results show that the V-like diverging wave along with air entrainment constitute the main characteristics of the wake. Air cavity of various scales is captured and tracked by the cavity-detection algorithm. Thus, the spatial and temporal distribution of the number and volume of air cavity is obtained in the simulation. Different draft Froude numbers are considered to analyze their influence on the wake. The wave profile, distribution of air cavity, turbulence kinetic energy, and the air entrainment features of the wakes behind dry and wetted stern are compared quantitatively. Numerical results demonstrate the present solver is capable of reproducing the main characteristics of wake behind a high-speed transom stern.