Development of the loop method on long-fetch conditions in wind wave tank

Yusuke Uemura, Kindai University, Osaka, Japan, Naoya Suzuki, Kindai University, Department of Mechanical Engineering, Osaka, Japan and Naohisa Takagaki, University of Hyogo, Himeji 671-2280, Japan
It is important to develop an accurate model for estimating air-sea momentum, heat, and mass flux. Using a wind-wave tank is effective, because it allows accurate measurements of air-water fluxes in a steady wind turbulent flow field through laboratory experiments. However, the fetch is limited in the wind-wave tank experiments, and an approach to extend fetch in the laboratory is necessary. In this study, we aimed to establish the fetch extension method using three techniques. In first technique, we reproduced the waves at the outlet of the wind wave tank at the inlet using the wave generator. In the second technique, we used a blade adjusting mechanism for controlling wind with arbitral vertical distribution at the entrance of the wind wave tank to reproduce the wind at the outlet of the wind wave tank at the inlet. In the third technique, we used both the wave generator and the blade for reproducing wind and waves. As a result, we succeeded in developing the wave generation method and extending the fetch in the wind-wave tank.