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Macroturbulent structure of open‐channel flow over gravel beds
Author(s) -
Shvidchenko Audrey B.,
Pender Gareth
Publication year - 2001
Publication title -
water resources research
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.863
H-Index - 217
eISSN - 1944-7973
pISSN - 0043-1397
DOI - 10.1029/2000wr900280
Subject(s) - eddy , turbulence , geology , flume , open channel flow , bedform , flow (mathematics) , geomorphology , sediment transport , mechanics , geotechnical engineering , sediment , physics
The turbulent structure of open‐channel flow over a mobile gravel bed was investigated in an 8 m long, 0.3 m wide, and 0.3 m deep tilting flume. A flow visualization technique was used and complemented by measurements of flow velocity fluctuations near the bed. The experiments reveal that turbulent flow consists of a sequence of large‐scale eddies with a vertical size close to the flow depth, an average length equal to four to five depths, and a width of about two depths. The downstream motion of these eddies causes quasiperiodic fluctuations of the local flow velocity components. The development of longitudinal troughs and ridges on the mobile bed and preferential transport of bed particles along troughs are related to the effect of the eddies. The experimental results indicate that the depth‐scale eddies are an important turbulence mechanism contributing to sediment transport.