Behavior of Oil Film on Water Surface in Surface Tension Controlled Time Period

Abstract

The behavior of an oil film on calm water surface in the surface tension-controlled time period was studied experimentally.
Velocity distributions of oil film were measured by tracing the positions of talcum powder laid on the film surface. The maximum velocity was found in the intermediate region between the center and the periphery of oil film.
The velocity distributions of oil film can be classified into two cases. One is the case where the relative velocity distribution is independent of time and the other is the case where it varies with time, where the relative velocity is defined by the velocity relative to the value at periphery of oil film. These two velocity distributions can be discriminated by a parameter which is the product of the oil viscosity and the final thickness of oil film divided by the spreading coefficient of oil film. The time dependency of the spreading velocity of oil film is concluded to vary with the type of velocity distribution.