Turbulent Behavior below an Air-Water Interface Affected by Wall Bursting, Interfacial Shear Stress, and Interfacial Waves

Abstract

The momentum transfer across an air-water interface was experimentally studied in a horizontal rectangular channel. The water flow Reynolds number, based on a hydraulic diameter, was fixed at 11500, while the air flow Reynolds number was varied from 0 to 5000. The streamwise air flow velocity was measured by a hot-wire probe. For the water flow, streamwise and vertical velocities were measured by using a split-film probe. The behavior of streamwise turbulence intensities showed their dependence on the interfacial shear stress. On the other hand, the vertical turbulence intensities showed less dependence on the interfacial shear stress. When the interfacial waves were formed, the increased Reynolds stress near the interface was measured. As a possible explanation of this increased Reynolds stress, nonlinear motion caused by the nonuniform distribution of the interfacial shear stress was proposed.