大規模乱流構造の可視化と解析

Abstract

Tracer method was applied to visualize the three-dimensional structure of turbulent open-channel flow. The horizontal cross-section of the flow illuminated by light through thin slit wasshifted upward and downstream. At the same time, pictures of flow patterns were taken every halfa second by the camera mounted above the channel. Illuminated cross-section and the camera wereboth shifted downstream with mean velocity of the flow. Pictures obtained were processed bycomputer system and distribution of velocity vectors, rotation and two-dimensional divergence wereobtained concerning each horizontal cross-section of the flow.On the basis of these results, downward or upward motion of fluid such as boils, bursts or sweepswere illustrated precisely and their distribution in three-dimensional flow field and their relationwith eddy motions were made clear.