単独水制下流部に発生する大規模組織渦の瞬間的移流構造に関する研究

抄録

To investigate the instantaneous flow patterns around a single groyne, a scale model was installed in the shallow water channel and experiments were conducted by means of surface flow visualization technique. A particle tracking velocimetry (PTV) method has been developed for shallow flow conditions and has been adopted to estimate the instantaneous velocity fields to cope with the problem of a very high dynamic velocity range behind the groyne. Proper orthogonal decomposition (POD) is applied to obtain an effect of the fluctuating flow pattern and its coherent structures. Conditional sampling technique (CST) is also applied to reveal the advection properties of POD decomposed flow pattern. POD decomposed coherent patterns and their advection properties under submerged and emerged conditions. One of main results is the distribution of coherent vortices generated at the groyne tip due to high shear forces in the mixing layer between main stream and dead zone.