Slamming occurrence for a chemical tanker advancing in extreme waves modelled with the nonlinear Schrödinger equation

The relative motion and frequency of slamming occurrence for a chemical tanker advancing in irregular waves are studied in this work. The objective is to develop a numerical method for estimating the probability of slamming occurrence of a chemical tanker, under the two conditions: the relative vertical motion at the same longitudinal position of the ship being larger than the vertical distance from the still water to the concerned position, and the entry velocity exceeding one threshold velocity. Ship motions in extreme waves are firstly estimated by using a fully nonlinear time domain seakeeping programme, while the wave surface modelling is achieved by a nonlinear Schrödinger equation. Then, the probability of slamming occurrence on the bottom of a chemical tanker is predicted statistically based on the relative motions between the cross section of the ship and the wave surface. The numerical results are compared with the experimental data from model tests of a chemical tanker. The effects of the forward speed on the slamming occurrence are studied as well.