WAVE FORCES ACTING ON A SUBMERGED SPHERE DUE TO IRREGULAR WAVES

Abstract

This paper is intended to discuss the wave force acting on a submerged sphere in a progressive irregular wave field. The measured wave forces are decomposed into the drag and inertia forces using the Morison equation. The maximum wave force, the drag and inertia coefficients of individual waves defined by the zero-downcrossing method and characteristics of the maximal wave forces are mainly investigated.The variations of the successive wave heights and periods effect largely to the wave force. The inertia coefficients of x-directed wave force of the successive waves whose heights are increasing are shown to be larger than those of the successive waves whose heights are decreasing.The probability distribution of the maximal wave forces in the case that the drag force dominates over the inertia force is not similar to that of the wave height. Then, the mean, mean one-third and mean one-tenth largest values of the maximal wave forces cannot be predicted with the mean, mean one-third and mean one-tenth highest waves, respectively.