DEPTH-AVERAGED OPEN-CHANNEL FLOW MODEL

A general mathematical model is developed to solve unsteady, depth-ave raged equations. The model uses boundary-fitted coordinates, includes effective stresses, and may be used to analyze sub- and supercritical flows. The time differencing is accomplished using a second-order accu rate Beam and Warming approximation, while the spatial derivatives are approximated by second-order accurate central differencing. The equat ions are solved on a nonstaggered grid using an alternating-direction- implicit scheme. To enhance applicability, the equations are solved in transformed computational coordinates. The effective stresses are mod eled by incorporating a constant eddy-viscosity turbulence model to ap proximate the turbulent Reynolds stresses. As is customary, the stress es due to depth-averaging are neglected. Excluding recirculating flows , it is observed that in most cases the effective stresses do not sign ificantly affect the converged solution. The model is used to analyze a wide variety of hydraulics problems including flow in a channel with a hydraulic jump, flow in a channel contraction, flow near a spur-dik e, flow in a 180 degrees channel bend, and a dam-break simulation. For each of these cases, the computed results are compared with experimen tal data. The agreement between the computed and experimental results is satisfactory.