Numerical analysis of initial stage of plate impact on water surface

The hydrodynamic loads originated during the water entry of a two-dimensional flat plate are investigated. The plate is initially floating on the free surface and is assumed to start suddenly its vertical motion. The liquid is ideal and incompressible, and gravity and surface tension effects are not taken into account. A numerical model able to describe the unsteady free surface flow generated by the plate impact is developed and the resulting hydrodynamic loads are estimated. The latter are compared with their asymptotic behaviour for small time, derived in a previous work. It is shown that, aside from an initial transient during which the numerical solution is not available, the theoretical estimate of the loads very well agrees with the numerical results, at least until the plate depth is of the order of 1/100 of the plate breadth. Subsequently the theoretical estimate is no longer reliable as the assumptions made in their derivation are no longer valid.