Kohei Shibuya

Study on Behavior of the Human Body while Swimming in a Wave Field

Naoyuki Inukai

 Since many water accidents occur every year in Japan, investigations and analyses of accidents are conducted in various water areas. Previous studies have reproduced the water surface, waves, and currents at the location of a water-related accident but considered the drowning of a human body as an approximation. Therefore, a numerical model is necessary to understand the water surface fluctuation and the vertical behavior of the human body before drowning. The purpose of this study is to develop a numerical model for understanding the vertical behavior of the human body in a wave field, and to verify the certainty of the numerical model through experiments.
 A numerical model was developed to understand the vertical behavior of the human body during water level fluctuations. Experiments were conducted in a swimming pool to verify the numerical model and to understand the behavior of the human body under the assumption of falling water and sinking water. Comparison of calculated and experimental values confirmed similar behavior of the human body in static water, assuming falling water and sinking water.
 In order to understand the behavior of the human body in relation to water surface fluctuations in a wave field, an experiment was conducted in a wave-making channel using a plastic bottle as a pseudo-human body. Comparison of calculated and experimental values showed that the experimental and calculated values differed in the amount of rise and fall of the pseudo-human body in response to water surface fluctuations, but the timing of rise and fall was similar. The numerical model constructed for the behavior of water surface fluctuations in a wave field and the behavior of the human body before drowning can be used to determine the timing of water surface fluctuations and respiration. The above results verify the certainty of the numerical model, and the drowning situation of the human body can be grasped in more detail by using the numerical model.