This experiment was designed to study breaking waves dynamics.

A wave-maker paddle produces multiple waves that overlap at a certain fetch resulting in a spilling or plunging breaker. Breaking process is captured by digital video cameras which are the part of the Particle Image Velocimetry (PIV) system. The basic idea is that we mix some silver dust into the water and highlight it with a laser sheet. Video cameras are taking two images few milliseconds apart (fig.1.). Based on these images and using cross-correlation based algorithm fluid velocity vectors field can be reconstructed.

Figure 1. Two images of wave breaking process taken about 5 milliseconds apart.

There is a variety of ways this data can be processed and presented. On figure 2 (left and right) components of velocities (horizontal and vertical) are shown separately on color maps. After some analysis turbulent kinetic energy can be obtained as well (fig 3).

Figure 2. Horizontal (left) and vertical (right) velocities obtained using PIV technique. Positive directions are left and up, wave propagates to the left.

Figure 3. Breaking wave turbulent kinetic energy distribution.

This briefly describes a flow visualization method that is actively used in ASIST laboratory ongoing research.