Print Email Facebook Twitter Hydrodynamic processes in sharp meander bends and their morphological implications Title Hydrodynamic processes in sharp meander bends and their morphological implications Author Blanckaert, K. Faculty Civil Engineering and Geosciences Date 2011-01-29 Abstract The migration rate of sharp meander bends exhibits large variance and indicates that some sharply curved bends tend to stabilize. These observations remain unexplained. This paper examines three hydrodynamic processes in sharp bends with fixed banks and discusses their morphological implications: secondary flow saturation, outer-banks cells, and inner-bank flow separation. Predictions from a reduced-order hydrodynamic model show that nonlinear hydrodynamic interactions limit the growth of the secondary flow. This process is called the saturation of the secondary flow. For outer-bank cells and inner-bank flow separation, the analysis relies on experimental findings from flume studies in channels with fixed and mobile beds. The experiments reveal that outer-bank cells exist near steep as well as shelving banks and amplify with increasing steepness and roughness of the outer bank, and especially with increasing curvature. The effects of flow separation at the inner bank are found to be strongly conditioned by flow-sediment interactions, which lead to an increased scour depth near the outer bank and increased velocities near the toe of that bank. Overall the results suggest that secondary flow saturation and outer-bank cells tend to inhibit meander migration, whereas inner-bank separation may enhance migration. The relative importance of these three hydrodynamic processes depends on hydraulic, geometric, and sedimentologic conditions, which is consistent with the large variance in observed migration rates. The results suggest that large shallow rivers have the most dynamic meandering behavior, while the occurrence of stabilized meanders seems to be favored in narrow rivers. Subject meander migrationriver bendsecondary flowflow separationmorphologyhydrodynamics To reference this document use: http://resolver.tudelft.nl/uuid:d9f29114-b6f9-4155-9e83-2fe32f0e03df DOI https://doi.org/10.1029/2010JF001806 Publisher American Geophysical Union Embargo date 2011-07-29 ISSN 0148-0227 Source Journal of Geophysical Research, 116, 2011 Part of collection Institutional Repository Document type journal article Rights (c) 2011 Blanckaert, K.American Geophysical Union Files PDF Blanckaert_2011.pdf 2.75 MB Close viewer /islandora/object/uuid:d9f29114-b6f9-4155-9e83-2fe32f0e03df/datastream/OBJ/view