ABSTRACT
Forlow-solubilitygasessuchasCO2 and O2 (but not for extremelysolublegasessuchasNH3), the resistance on the water sideusuallydominatesgastransferacrossair-waterinterfaces andthereforethegastransfermechanismhastobeclariŸed inrelationtotheturbulencestructureonthewaterside.Ina turbulentžowwithanunshearedžatair-waterinterface,turbulenceismainlygeneratedinthebulkwateržowawayfrom theinterface,asshowninFigure36.1a.Komorietal.(1982)Ÿrst measuredturbulencequantitiesnearthefreesurfaceinafully developedopen-channelžowbymeansofalaser-Dopplervelocimeter(LDV),andsuggestedthatenergy-containingeddiesare extremelyelongatedlongitudinallyandlaterallybythepresence ofthefreesurfaceandintermittentlyrenewthefreesurface. Furthermore,Komorietal.(1989)clariŸedthatthesurfacerenewaleddiesoriginateinburstingmotionsgeneratedinthe bottomwallregion,thatis,energy-containingturbulenteddies
ejectedbyburstingphenomenarisefromthebu§erregion towardtheinterfacial(outer)regionandarriveatandrenewthe freesurface.›eyalsoshowedthatthesurface-renewaleddies controltheCO2 transfer across the free surface on the liquid side andthegastransfercoe®cientonthewatersidekL is proportional to the square root of the surface-renewal frequency.
