NUMERICAL SIMULATION OF WAVE DEFORMATION AND OVERTOPPING OVER NATURAL REEF USING VOF METHOD

摘要

Wave overtopping-caused disasters have occurred around revetments in Okinawa islands, which are one of the typhoon-prone areas in Japan and are mainly surrounded by coral reefs. Countermeasures against wave overtopping are important from the viewpoint of disaster prevention and the design of coastal structures. The main purpose of this study is, therefore, to numerically examine wave deformation over a natural reef and wave overtopping around a road revetment in main Okinawa Island using a two-dimensional numerical wave flume “CADMASSURF”based on a VOF method. The numerical results reveal that the CADMAS-SURF is able to simulate wave deformation over the reef including wave breaking and wave overtopping around the revetment appropriately and wave overtopping characteristics are greatly affected by bottom topography in front of the revetment. In addition, two methods to estimate the wave overtopping quantity by integrating water volume behind the revetment and by calculating horizontal discharge flux at a vertical line over it are proposed in this study. The time variations of the wave overtopping quantities calculated by the two methods are found to be similar in the case of large overtopping quantity.