Numerical Simulation of the Effect of Weir Magnification on Hydraulic and Hydrodynamic Characteristics in Diversion Dams

Abstract

Since the geometry of duck tip overflows will complicate the problem for theoretical and practical purposes, it is crucial to study the magnification and hydraulic change of flow on these overflows. In this study, the effect of these changes on the hydraulic and hydrodynamic properties of the flow was investigated by numerical simulation using FLOW3D software by changing the overflow shape from linear to duck tip with magnifications 2 and 3. Dimensional analysis extracted dimensionless ratios and the relationship between variables in the experiments was determined. The results of comparing the numerical model with the laboratory model showed that the maximum error obtained from numerical simulation for the overflow coefficient of overflows is 12%. The permeability coefficient in the linear overflow with magnification 1 first had an increasing trend and then a decreasing trend. From a relative head greater than 0.6, the permeability coefficient was proved to be 0.7 for experimental data and 0.75 for simulation data. In the overflow, with a magnification of 2 to a relative head of 0.4, there was an increasing trend and from a relative head greater than 0.4, there was a decreasing trend. In the overflow with magnification 3, the permeability coefficient always decreases with increasing the relative head.

Keywords

• duck tip overflow
• flow control
• hydraulic
• relative head
• water permeability