Flow separation model for the water impact problem

The present paper proposes a new ow separation model for the water impact problem which is here solved through by a potential ow model with fully non-linear bound- ary conditions at the free-surface. The unsteady boundary value problem is numerically solved through a hybrid BEM-FEM approach where a boundary element method is coupled to a sim- plied nite element method for describing the thinnest part of the jet. In the water entry of bodies with smoothly curved surface, the point where the ow detaches from the body contour is unknown and has to be computed as a part of the numerical solution. For this reason, the hybrid BEM-FEM approach is here extended to include a ow separation model based on a kinematic criterion. The proposed model is applied to the water entry of dierent smoothly curved body with a constant vertical velocity. Numerical results show the capability of the formulation to accurately describe the free-surface evolution and pressure distribution as well as to provide a consistent prediction of the ow separation.