Saturation of curvature-induced secondary currents in relatively sharp bends: a two-dimensional modelling approach

Secondary currents occurring in channel bends have manifold implications in river hydraulics. In reduced-order models, the typical parametrizations of helical flow assume their magnitude to increase linearly with the channel curvature, although this is valid only in mild-curvature bends. In sharper bends, the non-linear interaction between the primary and the second-ary flow flattens the vertical profile of longitudinal velocity component, thus reducing the source mechanism of the secondary current. Established models for this so-called “saturation effect” all refer to the channel centreline. In this work, a pure 2D implementation of a saturation model is included in a Finite Element depth-averaged hydrodynamic model based on a Cartesian reference frame.