000161939 001__ 161939
000161939 005__ 20181203022242.0
000161939 0247_ $$2doi$$a10.1029/2009WR008303
000161939 022__ $$a0043-1397
000161939 02470 $$2ISI$$a000281634600002
000161939 037__ $$aARTICLE
000161939 245__ $$aTopographic steering, flow recirculation, velocity redistribution, and bed topography in sharp meander bends
000161939 260__ $$bAmerican Geophysical Union$$c2010
000161939 269__ $$a2010
000161939 336__ $$aJournal Articles
000161939 500__ $$a[748]
000161939 520__ $$aThe bed topography and associated flow field are investigated in a laboratory configuration with parameters that are representative for sharp natural meander bends. Zones of inward mass transport are characterized by a quasi-linear transverse bed profile, whereas zones of outward mass transport, induced by pronounced curvature variations, are characterized by a quasi-horizontal shallow point bar at the inside of the bend, a deep pool at the outside, and an increase in overall cross-sectional area. These quasi-bilinear bed profiles can be attributed to the curvature-induced secondary flow that is confined to the pool. Topographic steering, mainly due to mass conservation, concentrates the major part of the discharge over the deepest zones of the bend. But the pattern of depth-averaged velocities, which is relevant with respect to the development of the bed topography, does not show maximum values over the deepest zones. A term-by-term analysis of the depth-averaged streamwise momentum equation reveals that the water surface gradient is the principal mechanism with respect to flow velocity redistribution, although inertia and secondary flow are also processes of dominant order of magnitude. A required condition for the occurrence of adverse pressure gradients and flow recirculation due to planform curvature variations is established. A different type of flow recirculation, due to a subtle feedback between the flow and the bed topography, occurs over the point bar. The neglect of the influence of vertical velocities impinging on the bed in models for sediment transport is identified as a major shortcoming in the modeling of the morphodynamics of meandering river channels.
000161939 6531_ $$aOpen-Channel Bends
000161939 6531_ $$aCurved Open Channels
000161939 6531_ $$aSediment Transport
000161939 6531_ $$aRiver Bends
000161939 6531_ $$aTurbulence Measurements
000161939 6531_ $$aAlluvial Channels
000161939 6531_ $$aSecondary Flow
000161939 6531_ $$aModel
000161939 6531_ $$aSimulation
000161939 6531_ $$aSeparation
000161939 700__ $$g112543$$aBlanckaert, K.$$0241199
000161939 773__ $$j46$$tWater Resources Research$$k9
000161939 909C0 $$xU10263$$0252079$$pLCH
000161939 909C0 $$xU10263$$0255473$$pPL-LCH
000161939 909CO $$particle$$pENAC$$ooai:infoscience.tind.io:161939
000161939 917Z8 $$x182729
000161939 937__ $$aEPFL-ARTICLE-161939
000161939 973__ $$rNON-REVIEWED$$sPUBLISHED$$aEPFL
000161939 980__ $$aARTICLE