Relationship between surface velocity divergence and gas transfer in open-channel flows with submerged simulated vegetation

7th International Symposium on Gas Transfer at Water Surfaces

Sanjou, M.^1 ; Okamoto, T.^1 ; Nezu, I.^1

Department of Civil and Earth Resources Engineering, Kyoto University, Kyoto, Japan^1

关键词: Air water interfaces;    Bottom roughness;    Coherent vortices;    Gas concentration measurement;    Shear instability;    Submerged vegetation;    Surface velocity;    Vegetation density;   

Others  :  https://iopscience.iop.org/article/10.1088/1755-1315/35/1/012016/pdf
DOI  :  10.1088/1755-1315/35/1/012016

来源: IOP

【 摘 要 】

Velocity and gas concentration measurements were carried out to reveal gas transfer phenomena in open-channel turbulent flows with flat bottom and submerged vegetation bottom conditions. A large-scale coherent vortex appears near the vegetation top due to shear instability, and the submerged vegetation was found to promote gas transfer beneath the air- water interface. Furthermore, we revealed a great dependency of gas transfer on vegetation density. The present measurement results propose a new surface divergence model with wide generality, connecting reasonably the gas transfer velocity and the surface divergence intensity in open-channel flows, irrespective of bottom roughness conditions.