Visualization and picture processing of turbulent flow

The tracer method was used to visualize the three-dimensional structure of turbulent open-channel flow. A horizontal cross-section of the flow was illuminated by light passing through a thin slit. The illuminated cross-section was shifted upward, and at the time, successive pictures of flow patterns were taken. The picture-taking system was then shifted in downstream direction to follow the flow structures. The pictures obtained were processed by computer. Various kinds of physical properties of the flow were quantitatively evaluated and displayed as graphical outputs. These results contribute to the elucidation of the three-dimensional structure of turbulent open-channel flows.