Calculation of Potential Flow About Three-Dimensional Bodies in Shallow Water with Particular Application to Ship Maneuvering

Abstract

A combined two-and three-dimensional method is described for computing the potential flow about a three-dimensional body floating in the free surface in shallow water of infinite extent. The free surface is replaced by a rigid wall, and the problem then corresponds to the motion of a double body between two parallel walls. We utilize the fact that the flow is approximately two-dimensional in the middle part of a ship. The bow and stern region, however, are treated separately to take care of the end effects, which are very important in shallow water. Compared with a three-dimensional computation for the whole body, both the computer time and the necessary storage space are reduced. Numerical results of added-mass coefficients are given for circular and rectangular docks floating in the free surface and for prolate spheroids and a tanker-type ship (Tokyo Maru)for different water depths. Calculations of squat for Tokyo Maru are also presented.