Depth-Averaged Numerical Modeling for Curved Channels

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Without some correction for the interaction between lateral curvature and vertically nonuniform velocity, depth-averaged numerical models cannot predict the gradual migration of high velocity toward the outside of channel bends. Conventional depth-averaging does not account for the curvature-induced secondary flow that gives rise to the migration. To remedy this deficiency, a secondary flow correct ion (SFC) has been developed and incorporated in the two-dimensional STREMR code. The secondary governing equation contains two empirical coefficients, and these have been adjusted to make STREMR predictions agree with observed velocity profiles for a single 270-deg bend. Without further adjustment, the SFC yields comparable accuracy for multiple-bend predictions in two other channels with depth, curvature, and bottom friction different from the 270-deg case. This suggests that the SFC may be useful in general for bendways with small curvature, gentIe side slope, and moderate bottom friction.