000182757 001__ 182757
000182757 005__ 20190324182641.0
000182757 0247_ $$2doi$$a10.1002/esp.3324
000182757 022__ $$a0197-9337
000182757 02470 $$2ISI$$a000320036800004
000182757 037__ $$aARTICLE
000182757 245__ $$aFlow separation at the inner (convex) and outer (concave) banks of constant-width and widening open-channel bends
000182757 260__ $$aHoboken$$bWiley-Blackwell$$c2013
000182757 269__ $$a2013
000182757 300__ $$a21
000182757 336__ $$aJournal Articles
000182757 500__ $$a[890]
000182757 520__ $$aThere is a paucity of data and insight in the mechanisms of, and controls on flow separation and recirculation at natural sharply-curved river bends. Herein we report on successful laboratory experiments that elucidate flow structure in one constant-width bend and a second bend with an outer-bank widening. The experiments were performed with both a flat immobile gravel bed and mobile sand bed with dominant bedload sediment transport. In the constant-width bend with immobile bed, a zone of mainly horizontal flow separation (vertical rotational axis) formed at the inner bank that did not contain detectable flow recirculation, and an outer-bank cell of secondary flow with streamwise oriented rotational axis. Surprisingly, the bend with widening at the outer bank and immobile bed did not lead to a transverse expansion of the flow. Rather, flow in the outer-bank widening weakly recirculated around a vertical axis and hardly interacted with the inner part of the bend, which behaved as a constant-width bend. In the mobile bed experiment, downstream of the bend apex a pronounced depositional bar developed at the inside of the bend and pronounced scour occurred at the outside. Moreover the deformed bed promoted flow separation over the bar, including return currents. In the constant-width bend, the topographic steering impeded the generation of an outer-bank cell of secondary flow. In the bend with outer-bank widening, the topographic steering induced an outward expansion of the flow, whereby the major part of the discharge was conveyed in the central part of the widening section. Flow in the outer-bank widening was highly three dimensional and included return currents near the bottom. In conclusion, the experiments elucidated three distinct processes of flow separation common in sharp bends: flow separation at the inner bank, an outer-bank cell of secondary flow, and flow separation and recirculation in an outer-bank widening.
000182757 6531_ $$aflow separation; open-channel bend; experiments; morphology; laboratory
000182757 700__ $$0241199$$aBlanckaert, Koen$$g112543
000182757 700__ $$aKleinhans, M. G.
000182757 700__ $$aMcLelland, S. J.
000182757 700__ $$aUijttewaal, W. S. J.
000182757 700__ $$aMurphy, B. J.
000182757 700__ $$aVan deKruijs, A.
000182757 700__ $$aPasrons, D. R.
000182757 700__ $$aChen, Q.
000182757 773__ $$j38$$k7$$q696-716$$tEarth Surface Processes and Landforms
000182757 8564_ $$s4150819$$uhttps://infoscience.epfl.ch/record/182757/files/2012-890_Blanckaert_Kleinhaus_McLelland_Uijttewaal_Murphy_vandeKruijs_Parsons_Chen_Flow_Separation_at_the_inner_and_outer_banks.pdf$$yn/a$$zn/a
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000182757 917Z8 $$x206365
000182757 937__ $$aEPFL-ARTICLE-182757
000182757 973__ $$aEPFL$$rNON-REVIEWED$$sPUBLISHED
000182757 980__ $$aARTICLE