Abstract
We propose a simple numerical method to describe the air-water gas transfer at high Schmidt number. A numerical simulation is carried out in terms of the advection-diffusion equation using interfacial velocities obtained from a direct numerical simulation of open-channel turbulent flow. The present numerical method can describe the high Schmidt number air-water gas transfer driven by turbulence dynamics of the open channel flow. The numerical results show the surface divergence on the air-water interface to promote effectively the interfacial gas flux. Characteristics of surface-renewal eddies are found on the basis of cross-correlation coefficients between the interfacial gas flux and turbulent quantities such as the surface divergence and the vorticities.
