It is difficult to predict theoretically the impulsive wave pressure because of the variety in the design of breakwaters. Under such a situation, the criteria generating the impulsive wave pressure are described in the design manual. In the recent years, researches and developments of the numerical wave tank are gradually advanced and the wave transformation prediction simulators including wave breaking without any empirical formula are established. However the large size calculations becomes capable because of the hardware developments. In this report, the validity of the impulsive wave pressure calculations is verified by using the numerical wave tank based on VOF method, and the possibility of the practical application is investigated by calculating a model with large number of meshes. This numerical tank includes the gas-liquid two phase flow model, and the results of calculated impulsive wave pressure are compared. The main conclusions are the following:
1)The 3-D numerical wave tank was developed based on the 2-D type numerical wave flume proposed by the research group for the CADMAS- SURF.
2)The advanced deformation scheme for breaking waves was proposed and the validity of breaking criteria under uniform slope seabed was confirmed.
3)The treatment of numerical noise of the 2D numerical flume was applied to this 3-D numerical tank and the numerical results agreed well with experimental results.
4) The cause of the numerical noise of single phase flow model was clarified by using the gas-liquid two phase flow mode. The noise was induced by disagreement of water surface conditions in a gas area in the single phase numerical tank.
5) The large size simulations resembling the field condition were conducted, and the generation of impulsive wave pressures was confirmed. Furthermore, the local variation of the breakwater plane arrangement made the impulsive wave pressure larger.