高垣 直尚

<p>It is important to use a wind-wave tank for investigating the mechanism of the wind-wave development. Although the wind-wave tank is generally used for investigating the mechanism, the maximum fetch in the wind-wave tank is limited by the length of the wind-wave tank, where fetch means the length of the water surface by air blowing. Therefore, the purpose of this study is to develop the fetch extension method, which we called the air-side loop method. In this method, the vertical distribution of streamwise mean wind speeds at the air outlet is reproduced at the air inlet by the shutter. The results show that the air flow in long fetch condition can be reproduced by the method.</p>

<p>Liquid jet is used in industries. However, the relationship between pressurization and jet speed have never been established, because the jet phenomenon contains a lot of fluid dynamics factors, for example, physical property, container shape and profile of pressurization. The purpose of this study is, therefore, to develop the physical model for liquid jet ejection. We performed experiment and numerical simulation using ANSYS/FLUENT and MATLAB. We found high correlation between outlet velocity and pressure. Also, we found that the liquid jet is ejected as compressible liquid in the beginning but the behavior changes from compressible liquid to incompressible liquid over time.</p>

A three-dimensional direct numerical simulation (DNS) is applied to a wind-driven turbulence, and the effects of the water turbulence and Langmuir circulations on scalar transfer across the air-water interface are investigated. In order to capture the deformable interface, an arbitrary Lagrangian-Eulerian formulation (ALE) method is applied. The results suggest that Langmuir circulations emerge on the water side but that the scalar transfer across the air-water interface is mainly controlled by the water turbulence and the effect of the Langmuir circulations is relatively small.