On Wedge-Slamming Pressures

The water entry of a wedge has become a model test in marine and naval engineering research. Wagner theory, originating in 1932, predicts impact pressures, and accounts for contributions to the total pressure arising from various flow domains in the vicinity of the wetting region on the wedge. Here we study the slamming of a wedge and a cone at a constant, well-controlled velocity throughout the impact event. Using an in-house visualisation technique, we reveal that air-cushioning under the cone causes a significant deflection of the water surface prior to impact despite a large deadrise angle. Pressures at two locations on the impactor are measured during and after impact. Pressure time series from the two impactors are discussed using inertial pressure and time scales. The non-dimensionalised pressure time series are compared to composite Wagner solutions (Zhao & Faltinsen 1993). It is shown that, without a single free parameter, the space-averaged composite solutions reproduce the measurements near perfectly well, and a finite size of the sensor is why the peak pressure has a non-singular rise. In addition, we provide an experimental justification for approximations made in the inner-domain in existing literature, for extending Wagner model to three-dimensions.