A numerical study on the behavior of a supercritical flow over piano key side weirs

Abstract

Side weirs are a type of hydraulic structures that can be used as a deviator structure for controlling and dispensation of discharge in flood and high velocity flows. The flow on these structures is spatially varied flow type with decreasing discharge. Due to the applications of side weirs for transferring and controlling discharge in flood flows and considerable velocities, its very likely to have supercritical flow on these kind of structures. Piano key and labyrinth side weirs can be used, when the width of the weir opening is limited. The increase in side weir's effective length relative to its opening is one of the advantages of these side weirs. The majority of studies done on the Piano key weirs had been limited to experimental methods, due to the limited conditions of laboratory, high cost and recent development in numerical models, its important to simulate these weirs in fluid dynamics software’s. In this research side weirs with different plans have been simulated by FLOW-3D. The FLOW-3D numerical model has been calibrated and verified for simulating side weirs using experimental results. Determination and presentation of the relation between the kinetic energy correction factor () and the momentum correction factor (β), discharge coefficient for Piano key side weirs in supercritical flow and comparing the shapes of piano key side weirs are some of the results of this research. These results can be used in designing these side weirs.