In recent years, various terrorist incidents occurred in various parts of the world, anxiety spreading all over the world. Among the weapons that are concerned about diversion to terrorism, biological and chemical weapons are greatly fatal, leading to great social confusion. In addition, these weapons are particularly dangerous because they are relatively easy to manufacture. In terrorist attacks, many civilians are sacrificed, and it is difficult to predict the time and place to occur, so research and development of decontamination technology assuming emergency cases is an urgent task. However, research and development of various decontamination technologies through experiments are extremely difficult due to danger and legal restrictions. Therefore, research and development by numerical simulation is an effective investigation method. In this research, we aim to comprehensively predict the disinfestation process of toxic chemical agent in gas decontamination system.

　Breakwaters can be cited as one way to suppress and reduce the damage caused by tsunami disasters. However, conventional breakwaters have problems such as low strength against tsunamis larger than expected, and damage to the landscape. As one of countermeasures against these problems, submarine breakwaters have been proposed. Many researches on suppression of tsunami by traditional breakwaters have been conducted, but almost no tsunami suppression effect by underwater breakwater has been verified so far. Therefore, in this research, we investigate and verify the tsunami suppression effect of underwater breakwater by conducting numerical simulation using the particle method for the tsunami behavior when installing subsea breakwaters.

　As renewable energy gathers more attention as a response to the global warming problem, wind power generation is proliferating as powerful energy from the viewpoint of power generation cost. A wind farm (large-scale wind farm) that intensively arranges a plurality of wind turbines at one site is known as an operation means for increasing the economic efficiency of wind power generation. However, demerits also exist in the aggregate arrangement of the windmills. This is because interference of the windmill's wakeflow occurs and the windmill existing in the wakeflow can not receive enough wind for electricity generation, resulting in a decrease in the total electric power generation amount. Therefore, in this research, we focus on simulating interference avoidance of windmill late flow, and aim to contribute to improvement of total power generation amount in wind farm.