The Impact of Surface Contamination on the Flow Beneath Wind-Generated Waves

We report on an experimental study conducted to investigate flow characteristics in the near-surface layer beneath clean and surfactant-contaminated water surfaces in the presence of wind. The two-dimensional velocity field beneath the water surface was measured using particle image velocimetry. The water surface temperature measurements were made simultaneously using infrared imagery. The results show the existence of the viscous sublayer beneath both clean and contaminated water surfaces. Within the viscous sublayer in contaminated water, the mean streamwise velocity is 25–30% larger and the mean streamwise velocity gradients are more than a factor of two larger compared to that beneath clean water surfaces.