Analytical and Computational Challenges of Incompressible Flows at High Reynolds Number

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The Effects of Surfactants on Breaking Waves

Jim Duncan

                               Department of Mechanical Engineering, University of Maryland

Abstract: The effects of surfactants on mechanically generated breaking waves are studied experimentally. The waves are generated in a tank that is 11.8 m long, 1.1 m wide and 1.0 m deep. Wave profiles along the center plane of the tank are measured with an LIF technique that utilizes a high-speed digital movie camera. This measurement system is mounted on an instrument carriage that is set to move along the tank with the speed of the breaking crests. Measurements are performed with clean water and water mixed with various concentrations of the soluble surfactants Triton X-100 and Sodium Dodecyl Sulfate. Extensive measurements are also performed to characterize the dynamic properties of the water surface for each experimental condition. In clean water, the waves studied herein are dominated by surface tension and form spilling rather than plunging breakers. In the presence of a wide range of surfactant conditions, this process is changed only quantitatively from the clean-water case. However, in two of the surfactant conditions, two types of plunging breakers were formed. The physical reasons for the appearance of these plungers in terms of the measured dynamic surface properties are discussed.
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