Numerical and Experimental Study of the Wave Breaking Generated by a Submerged Hydrofoil

In the present paper the two-dimensional wavy flow generated by an hydrofoil moving beneath the free surface is experimentally observed and numerically studied. The numerical investigation is performed by means of a finite difference Navier-Stokes solver. The free surface is embedded in the computational domain and the flow either in air and in water are computed. The Navier-Stokes solver is coupled with a Level Set technique to captures the interface location. The presence of the hydrofoil is taken into account either by introducing suitable body forces on the grid points inside the body contour or by a new domain decomposition approach, developed to concentrate computational efforts in the free surface region. Experimental study concerns the wave breaking dominated by the ripples formation. The stages of the evolution of a breaking generated after the onset of a capillary wave train are visualized. For a fixed Froude number and angle of attack, the depth of the hydrofoil has been gradually varied, until the condition for incipient breaking has been reached. Depending on the condition of the experiment, the wave breaking can start from the forward face of the second or third wave crests, hence propagating to the first wave, leading to the full developed event.