Numerical Investigation of Wave-Body Interactions in Shallow Water

Abstract

DNV has Wasim (a module of HydroD) as a Rankine panel method potential flow solver originally developed for more concern to deep water analysis. Some attempts have been made to extend the capability of the program in shallow water. The stream function method is chosen and still in development for the current Wasim, but unphysical ?pumping? diffractions which may due to numerical problems have been observed. In the previous work, i.e. the project done in the last semester, the error was reproduced and some preliminary possible reasons were proposed.The main task of this thesis is to fix the bug and test the modification of the program. Then two sets of nonlinear free surface conditions will be implemented which together with the stream function method are purposed to improve the capability of the program when handling nonlinear problems. In final, these two approaches of the nonlinear free surface conditions will be evaluated by comparing with some experiment results. The evaluation process is mainly composed of two parts. Wave diffractions will be tested first by checking the wave loads on a fixed cylinder, and afterwards wave radiations will also be included where the motion responses of a LNG carrier will be studied. The numerical results calculated by Wasim will be compared with the experiment data collected from Huseby & Grue (2000) and the Extreme Seas project respectively.