a 2d numerical depth-averaged model for unsteady flow in open channel bends

the purpose of this paper is to present a 2d depth-averaged model for simulating and examining unsteady flow patterns in open channel bends. in particular, this paper proposes a 2d depth-averaged model that takes into account the influence of the secondary flow phenomenon through calculation of the dispersion stresses. the dispersion terms which arose from the integration of the product of the discrepancy between the mean and the actual vertical velocity distribution were included in the momentum equations in order to take into account the effect of the secondary current. this model used a time-splitting method for solving advection, diffusion and other momentum equation terms. the proposed model uses an orthogonal curvilinear coordinate system efficiently and accurately to simulate the flow field with irregular boundaries; it also used a finite volume projection method approach for solving the governing equation in a staggered grid. two sets of experimental data were used to demonstrate the model's capabilities. the comparison of the simulated water surface elevation with the measurements shows good agreement and indicates that inclusion of the dispersion terms improved the simulation results.