GAS TRANSFER PHENOMENA BENEATH AIR-WATER INTERFACE IN OPEN-CHANNEL FLOW WITH SMALL ASPECT RATIO

Abstract

This study describes gas transfer beneath air-water interface and related turbulence transport below the free-surface in open-channel flow with small aspect ratio. Simultaneous PIV-LIF measurements were conducted by using dual high-speed camera system which allowed us to evaluate gas transfer flux accurately on the basis of eddy-correlation method. It is found that the present transfer velocity becomes larger compared with previous experimental data obtained in the large aspect ratio condition. Furthermore, time-variation of bulge structure of dissolved gases and surrounding velocity vectors were visualized in order to understand turbulence contributions to gas transport.