TY - GEN
T1 - Flow evolution near the apex of two small stream confluences using large-scale particle image velocimetry
AU - Lewis, Quinn W.
AU - Rhoads, Bruce L.
N1 - Funding Information:
The research in this paper was partially supported by National Science Foundation (BCS 135-9911), the University of Illinois Research Board, and the University of Illinois Department of Geography and Geographic Information Science. Thanks to Jessica Z. Leroy, Muhammad Umar, Mingjing Yu, and William Andresen from University of Illinois and Cintia Ramón from University of Granada for assistance with field work. We appreciate the comments of an anonymous reviewer, which improved the quality of this manuscript.
Publisher Copyright:
© 2016 Taylor & Francis Group, London.
PY - 2016
Y1 - 2016
N2 - This study examines flow near the apex of two confluences with different geometries and hydrologic conditions. Characterization of flow at one of the confluences is based on Large Scale Particle Image Velocimetry (LSPIV) and Acoustic Doppler Velocimeter (ADV) measurements, whereas characterization at the other is based on LSPIV measurements only. At the first confluence, LSPIV and ADV measurements clearly show a zone of flow stagnation near the junction apex and a region of velocity deficit extending downstream from this stagnation zone into the center of the confluence. LSPIV reveals that shear layers exist on both sides of the stagnation zone and velocity-deficit region. Flow from the main channel moves slowly across the stagnation zone and is entrained into the tributary-side shear layer. LSPIV measurements at the second confluence indicate the lack of well-developed flow stagnation near the junction apex; instead, strong shear between the confluent flows generates well-defined 2D vortices. The results of this field study generally support hypotheses emerging from numerical simulations about the structure of flow near the apex region of confluences with different hydrological conditions.
AB - This study examines flow near the apex of two confluences with different geometries and hydrologic conditions. Characterization of flow at one of the confluences is based on Large Scale Particle Image Velocimetry (LSPIV) and Acoustic Doppler Velocimeter (ADV) measurements, whereas characterization at the other is based on LSPIV measurements only. At the first confluence, LSPIV and ADV measurements clearly show a zone of flow stagnation near the junction apex and a region of velocity deficit extending downstream from this stagnation zone into the center of the confluence. LSPIV reveals that shear layers exist on both sides of the stagnation zone and velocity-deficit region. Flow from the main channel moves slowly across the stagnation zone and is entrained into the tributary-side shear layer. LSPIV measurements at the second confluence indicate the lack of well-developed flow stagnation near the junction apex; instead, strong shear between the confluent flows generates well-defined 2D vortices. The results of this field study generally support hypotheses emerging from numerical simulations about the structure of flow near the apex region of confluences with different hydrological conditions.
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U2 - 10.1201/9781315644479-256
DO - 10.1201/9781315644479-256
M3 - Conference contribution
AN - SCOPUS:85015332670
SN - 9781138029132
T3 - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
SP - 1640
EP - 1647
BT - River Flow - Proceedings of the International Conference on Fluvial Hydraulics, RIVER FLOW 2016
A2 - Constantinescu, George
A2 - Garcia, Marcelo
A2 - Hanes, Dan
PB - CRC Press/Balkema
T2 - International Conference on Fluvial Hydraulics, RIVER FLOW 2016
Y2 - 11 July 2016 through 14 July 2016
ER -