Surfactants in the Wake of a Surface Ship and their Influence on Ambient Waves
Final technical rept. 1 Nov 88-30 Apr 91,
ROSENSTIEL SCHOOL OF MARINE AND ATMOSPHERIC SCIENCE MIAMI FL DIV OF APPLIED MARINE PHYSICS
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Field experiments have established that sufficient amounts of surface-active organic materials accumulate in the wake of a surface ship to cause significant reductions in the surface tension across certain portions of the wake vis-a-vis the ambient surface tension of seawater. Such accumulations of surfactant material are known to strongly damp ocean waves of less than 15 to 20 cm in wavelength. Hence, it seems probable that the observed accumulations of surfactant materials play a critical role in the formation and persistence of long, narrow, dead water region occurring the wake of a surface ship. Our objective was to synthesize a model that describes the distribution of surfactants in the wake of a surface ship and to determine the effects of this distribution on the ambient wave field. Major components of the model were to encompass sources of surfactant accumulation, causes of surfactant dissipation, and wave regeneration due to wind. A primary source of surfactant accumulation is thought to be bubble scavenging of surfactant materials from the water column. As input to the model, we conducted experimental studies to determine relationships among bubble size, bubble production rate, and volumetric concentrations and types of surface-active organic compounds in seawater to the rates at which these compounds were scavenged from the water column and deposited on the surface by the bubbles.
- Physical and Dynamic Oceanography
- Fluid Mechanics