title: Weakly breaking waves in the presence of surfactant micelles.
abstract: Mechanically generated weakly breaking waves were studied experimentally in clean water and water with a soluble surfactant whose bulk concentration was above the critical micelle concentration (CMC). For the surfactant case, the breaker, which forms a surface-tension-dominated spilling breaker in clean water [wave frequencies 1.42 to 1.15Hz , see Duncan, J. Fluid Mech. 379, 191 (1999)], ranges from a spiller at the highest frequency to an overturning wave with a plunging microjet at the lowest frequency. It is shown that this behavior is consistent with that of a wave in a pure liquid with a lower surface tension than water rather than water with a surfactant monolayer. The analysis of the geometrical characteristics of the breaking surface generated by the jet impact on the front face of the wave crest indicates a patch of more violent turbulence suggesting an increase of air-sea transfer compared to the clean water case.
authors.affiliation: Department of Mechanical Engineering, University of Maryland, College Park, MD 20742, USA. xliu@umd.edu
authors.forename: Xinan
authors.initials: X
authors.lastname: Liu
authors.forename: James H
authors.initials: JH
authors.lastname: Duncan