PARTICLE TRACKING VELOCIMETRY BENEATH WATER-WAVES - PART I - VISUALIZATION AND TRACKING ALGORITHMS

A novel particle tracking system working with a high particle concentr ation for the measurement of flow fields beneath water waves is descri bed. It features a 1-4 cm thick light sheet parallel to the main wave propagation direction so that the seeding particles stay long enough i n the illuminated area to enable tracking over several wave periods. A n area of up to 14.0 x 10.0 cm(2) is observed by a CCD camera with up to 200 fields/s. The polychromatic scattering theory of small particle s in a light sheet illumination is investigated, enabling the segmenta tion of individual particles at high particle concentration.