Author(s): De Marchis Mauro; Napoli Enrico
Linked Author(s):
Keywords: Compound channels; Meanders; Sinuosity; Stage-discharge curves; Numerical simulation
Abstract: A number of methods and formulae have been proposed in the literature to estimate the discharge capacity of compound channels. When the main channel has a meandering pattern, a reduction in the conveyance capacity for a given stage is observed, because of energy dissipations caused by secondary currents and the decrease of the ‘effective’ bed slope, due to the increase in the length of the channel. The assessment of discharges in meandering compound channels is usually obtained applying, with some adjustment, the same methods used for straight compound channels. To this aim, the sinuosity of the main channel is frequently introduced to account for its meandering pattern, although some methods rely on different geometric parameters. In the paper the stage-discharge curves are calculated and compared for three compound channels having identical cross section, bed slope and sinuosity but different planimetric patterns, in order to check if the sinuosity can be efficaciously used as the one and only parameter to account for meandering patterns. The substantial overlapping of the obtained stage discharge curves demonstrates the soundness of sinuosity as the parameter to be accounted for in empirical methods to assess conveyance capacity of meandering compound channels. Comparison of stage discharge curves in the meandering compound channels with those obtained in a straight channel having identical cross section clearly shows the reduction of discharges due to the presence of bends in the main channel. The simulations are carried out using a 3D finite-volume model that solves the RANS equations using a k-ε turbulence model. The numerical code is validated against experimental data collected in both straight and meandering compound channels.
Year: 2007