Simulation of meandering channel migration processes with an enhanced two-dimensional numerical model

Flow passing through meandering channels consists of a primary longitudinal flow and a secondary circulation. This secondary circulation transfers momentum to the outer bank in the upper part and to the inner bank in the lower part of the flow. This momentum transfer redistributes the primary flow and consequently flow accelerates at the upstream of the convex bank and the downstream of the concave bank and decelerates at the corresponding opposite banks. On the bottom of the channel, the secondary circulation directly transports bed load from the concave bank to the convex bank, whereas the surface flow convergences to the concave bank. As a consequence, the concave banks in meandering channels often endure severe bank erosion. Using the classic depth-averaged two-dimensional model to describe flow field in a meandering bend is not feasible because the depth-averaged velocity of the secondary flow is approximately zero, whereas the velocity could have a considerable value on the surface and bottom. Therefore, an enhanced two-dimensional numerical model was developed for this study and it consists of the simulations of flow field, sediment transport, and bank erosion. Copyright ASCE 2004.