Numerical simulations of breaking waves generated by a 3-D submerged hydrofoil

Abstract

Underwater structures near the water surface can induce disturbances, leading to wave breaking, which involves complex physical mechanisms. Building on previous studies, this paper conducts a 3-D simulation of breaking waves generated by a NACA0012 hydrofoil at different angles of attack. In contrast to earlier studies, which mostly concentrated on the hydrofoil’s macro-physical parameters like lift and drag, this study focuses on the dynamics of entrained bubbles after free surface breaking. The results indicate that at higher angles of attack, bubbles are swept to greater depths, and both the number and volume of the bubbles increase. By analyzing the bubble velocity data, it is found that the underwater bubble motion is primarily dominated by longitudinal movement, while transverse and vertical bubble velocities are symmetrically distributed. Additionally, vortex structures in the flow field are investigated using the third-generation vortex identification method, Liutex-Omega. It is observed that the vortex structures in the hydrofoil’s wake interact with those generated by free surface breaking downstream, reducing the survival time of large bubbles and increasing the number of small bubbles. Consequently, the bubble number density power law exponent shifts from −10/3–−9/2 as bubble radius increases.