Study on the interaction between free surface and flow using PIV

The interaction between the free surface and flow was evaluated measuring the velocity distribution and surface movement simultaneously. The jet interacted with the free surface, causing the wavy free surface condition. The flow under the free surface was visualized by a laser light sheet and small tracer particles. With image processing techniques, the movement of the free surface and the movement of the particles were simultaneously measured from the recorded images, resulting in the velocity distributions and surface locations. Then, the interactions between the flow and free surface were evaluated using the form of turbulent energy and surface-related turbulent values. By increasing the turbulent energy near the free surface, the fluctuations of the free surface height and the inclination of the free surface were increased. The image processing technique is found to be very useful to evaluate the interaction between free surface and flow.