Development of CIP/Cartesian Grid Method for Strongly Nonlinear Interaction between Free Surface and Floating Body

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This project was aimed at developing a OP (Constrained Interpolation Profile) based Cartesian grid method for quantitative prediction of strongly nonlinear seakeeping problems, such as ship motions in large-amplitude waves, resultant slamming on ship's bottom and flare, the green-water impact on deck, and so on. Dur ing the two years' project term, the following results have been obtained.(1) To improve the efficiency of the free surface calculation, a new interlace-capturing scheme, THINC (Tangent of Hyperbola for Interface Capturing) scheme, has been improved and implemented into the CIP/Cartesian grid code. Numerical simulation by the improved code on a modified Wigley model moving in large regular head waves has been carried out By comparing to the computed results obtained by using former CIP based interface-capturing scheme, the use of THINC scheme can siginificantly improve the prediction accuracy about the wave impact pressures on the deck and the ship motions.(2) A new method has been developed for the CIP/Cartesian grid code for computing actual ships. By this method, the body is approximated by distributing virtual particles on the surface. An algorithm has been designed to generate such particles from CAD date of a real ship with super structures. The efficiency of the method has been confirmed by numerical simulation of a container ship model (S-175).(3) For practical application purpose, a study on parallel computation technique using a PC cluster has been made. The pressure solution part of the CIP/Cartesian grid code has been parallelized. Further, visualization technique by POV-RAY has been developed for demonstrating the computed results.