Effects of surfactants on wakes of surface penetrating cylinders

White water, bubble wakes are the most apparent signature of surface ships and their extent is indicative of the degree of mixing in the wake. The coastal ocean generally contains levels of surfactants, due to ocean biologics and anthropomorphic inputs that affect bubble persistence. To investigate the effects of surfactants a series of experimental studies have been conducted on the evolution of white water wakes (WWW) generated by surface penetrating cylinders. The cylinder was towed at speeds ranging from 0.7 -- 2.4 m/s (Froude numbers of 1.02 to 3.50) with varying levels of surfactants that that decreased the surface tension to values comparable to those observed in the coastal ocean. Digital analysis of images collected with a video camera system was used to determine the characteristics of the WWW. It was found that the presence of surfactants increased the WWW area by a factor of two and caused a coalescence of groups of bubbles on the surface that persisted for very long times. It was also found that there is an apparent saturation effect whereby additional surfactant did not further increase the WWW area.