Calculation of transverse energy regime in curved channels ?
The development of a quasi two-dimensional model for simulating the transverse and longitudinal energy gradient effects on the streamwise flow regime in meandering river channels is reported. The mathematical formulation of the curved flow is based on the principle of minimum stream power, where the total flow energy rate was divided into two components; longitudinal and transverse energy components. The mechanisms by which the energy is dissipated has been formulated on the basis of boundary resistance (longitudinal and transverse), internal turbulent friction and secondary circulation. The resulting increase of the lateral energy dissipation rate in the flow is emphasised. A direct relationship between the lateral energy dissipation rate and the ensuing excess boundary resistance to flow is proposed. The procedure used in the numerical calculations is described in detail. The model has been applied successfully to channels with rigid boundaries and found to give accurate predictions for the velocity and shear stress distributions. Finally, the model has been applied to two different case studies representing quasi river channel situations; a water supply canal and a curved channel with mobile bed. On the basis of the good comparisons obtained with measurements, it can be concluded that the model can be applied successfully to flow situations in river systems.
meandering rivers boundary resistance secondary circulation shear stress mathematical modelling finite difference method