Prediction of Spray Root Location on a Deforming Wedge during Vertical Water Entry*

The phenomenon of slamming of ocean-going craft traveling at high-speed restricts the operating envelope of the vessel. The slamming (or impact) process is simulated using a wedge shape, that models a single section of the hull, vertically dropped into calm water. The model used in this study has a flexible bottom that deforms upon impact with the free surface. Much previous work done in this field assumes a rigid wedge. In the current study, Wagner’s method for 2-D water entry is extended to analyze a flexible wedge. The deformed shapes of the wedge at each timestep are taken from an experiment conducted in the lab. Second, third, and fourth order polynomial fits have been applied to deformation data to model the form of the bottom. The fourth order fit most accurately models the experiment and is used in calculating the location of the waterline. The calculated waterline locations are compared with the actual waterline location from the experiment, which is determined using image processing from high-speed cameras that film the impact process. The comparison agrees well, but discrepancies occur due to the linear assumptions in Wagner’s theory.