TY - JOUR
T1 - Field investigation of three-dimensional flow structure at stream confluences 2. Turbulence
AU - Sukhodolov, Alexander N.
AU - Rhoads, Bruce L
PY - 2001/9/12
Y1 - 2001/9/12
N2 - Stream confluences are among the most highly turbulent locations in fluvial systems. This paper examines the three-dimensional structure of turbulence at three stream confluences in east central Illinois. The analysis focuses on the characteristics of turbulence both within the shear layer and in the ambient flow. Results show that at the upstream end of each confluence the shear layer occupies a limited portion of the flow cross-sectional area, but turbulence kinetic energy within this layer is 2-3 times greater than the turbulence kinetic energy of the ambient flow, which has turbulence characteristics similar to those for flow in straight channels. Turbulence within the shear layer can be characterized as quasi-two-dimensional in the sense that large-scale turbulence generated by transverse shear is predominantly two dimensional, whereas small-scale turbulence associated with bed friction is three dimensional. Spectral analysis suggests that the structure of fluid motion within the shear layer differs for confluences with symmetrical versus asymmetrical planforms. The shear layer dissipates rapidly as flow enters the downstream channel, even though a well-defined mixing interface persists at downstream locations.
AB - Stream confluences are among the most highly turbulent locations in fluvial systems. This paper examines the three-dimensional structure of turbulence at three stream confluences in east central Illinois. The analysis focuses on the characteristics of turbulence both within the shear layer and in the ambient flow. Results show that at the upstream end of each confluence the shear layer occupies a limited portion of the flow cross-sectional area, but turbulence kinetic energy within this layer is 2-3 times greater than the turbulence kinetic energy of the ambient flow, which has turbulence characteristics similar to those for flow in straight channels. Turbulence within the shear layer can be characterized as quasi-two-dimensional in the sense that large-scale turbulence generated by transverse shear is predominantly two dimensional, whereas small-scale turbulence associated with bed friction is three dimensional. Spectral analysis suggests that the structure of fluid motion within the shear layer differs for confluences with symmetrical versus asymmetrical planforms. The shear layer dissipates rapidly as flow enters the downstream channel, even though a well-defined mixing interface persists at downstream locations.
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U2 - 10.1029/2001WR000317
DO - 10.1029/2001WR000317
M3 - Article
AN - SCOPUS:0034871037
SN - 0043-1397
VL - 37
SP - 2411
EP - 2424
JO - Water Resources Research
JF - Water Resources Research
IS - 9
ER -