Transport across a turbulent air-water interface

Abstract

Turbulence structure in the immediate vicinity of the air - water interface has a dominant influence on the mass transfer across it. In this work, investigations on near-surface turbulence and mass-transfer rate were carried out for two distinct flow conditions: one with turbulence generated from beneath the interface, the other via wind shear from above the interface. Turbulence measurement with respect to the fluctuating interface was performed and Hanratty's β, the gradient of the linear variation of vertical velocity at the interface, was quantified. It is found that incorporating a near-surface turbulence parameter such as β provides a reasonable model for interfacial mass transfer, applicable to the two vastly different flow conditions studied.