Distribution of primary and secondary currents in sine-generated bends

Abstract

The secondary circulation in a meandering channel redistributes the velocity over the bend. However, the shift of primary flow by secondary currents is not quantitatively understood, due to the difficulty in isolating the role of curvature-driven secondary flow from that of topography-driven secondary flow in bed-deformed meanders. The influences of curvaturedriven and topography-driven secondary currents on the redistribution of primary flow in sine-generated meandering channels were examined by CCHE2D. The model is calibrated using data measured in two sets of laboratory experiments including flat-bed flow and mobile-bed flow. Analysis indicated that topography-induced current mainly contributes to the redistribution of primary flow from inner to outer bank in the curved channels, rather than the secondary flow driven by curvature.

The Straightening of a River Meander Leads to Extensive Losses in Flow Complexity and Ecosystem Services

“…The morphodynamic connections to river curvature include the generation of transverse, or secondary circulation patterns [31,32], which establish feedback loops between the dynamics of sediment transport and morphology of bed topography [33,34]. Our experiments documented how the loss of secondary circulation cells was associated with changes patterns of maximum velocities in three directions and a loss of vortices others have shown useful for biota.…”