تخمين سرعت متوسط عمقي و تنش برشي در كانال مثلثي باز

Estimation of Depth-Averaged Velocity and Boundary Shear Stress in a Triangular Open Channel

The proposed method by Shiono and Knight (SKM) is able to predict the lateral depth-averaged velocity and shear stress distribution in open channels. The SKM is needed to be calibrated. The calibration parameters are friction factor/, lateral eddy viscosity X, and secondary flow F. In practical problems, the assumption of X =0.07 from among these is considered as a standard value for the eddey viscosity. Thus, the accuracy of the depth- avergad and the shear stress distributions using SKM will be subject to the determination of /ʹand F. In the present paper, we present the secondary flow cell pattern (F) and friction factor distribution (/) in a straight prismatic triangular channel with a uniform roughness. The trial and error approach is used to define the best pattern of friction factor to produce the most appropriate results. The results of predicted depth-averaged velocity as well as shear stress distributions obtained from SKM as compared to measured values indicate that SKM can accurately predict the velocity and shear stress distributions if the two coefficients of/and F are chosen based on accurate patterns.