Measurements of velocity profiles in the aqueous boundary layer at a wind-driven water surface

A two-dimensional flow-visualization technique for the investigation of wind-induced currents in the boundary layer beneath the water surface is presented. Experiments were conducted at the Heidelberg wind-wave facility at conditions where either wave motion was suppressed by surfactants or was not present because of low wind speeds. A PIV setup enables the calculation of flow vector fields and velocity profiles in an area of 4mm beneath the interface. Parameters of this layer, such as the friction velocity were deduced from these profiles.