Two-Dimensional Wind Setup of Oil on Water

The geometry of an oil wedge that floats on water and is retained by a barrier depends on the wind and current forces acting on the oil. An investigation of the two-dimensional setup of floating oil retained by a rigid barrier and subjected to a wind stress was conducted. An analytical expression for the oil wedge thickness as a function of oil properties, wedge length and wind stress or wind velocity was developed. This expression was then experimentally verified in a two-dimensional wind-wave flume. Experiments were conducted for a range of wind speeds using three oils with different density and viscosity. The air-oil interfacial stress for a smooth interface is the same as that for wind over a smooth water surface. However, the development of waves in the oil significantly increases the interfacial stress and resulting setup. A prediction equation is presented for conditions when waves exist but further research on the nature and effects of waves at the air-oil interface is needed. Interfacial stresses evaluated from the setup prediction equation were in agreement with stress values determined from wind velocity profile measurements and the Karman-Prandtl equations.