Numerical Modeling of Hydraulic Performance of Piano Keys Overflows with Different Geometry

Abstract

Abstract. In this study, the properties of hydraulic flow were done on the piano keys overflow in the various geometric models by three-dimensional mathematical model of 3D Flow. The Hydraulic properties regarded in this study are the flow rate flood coefficient . In this study, the flow was considered kind of permanent, perturbation flow and incompressible fluid. The perturbation model used in this study is . Determination of free level profile was done by the use of VOF. The boundary model conditions include input level, output level, wall and free surface flow. The results show that the mathematical model accurately is capable of modeling this type of overflow. The results also show that the the piano keys overflow has higher discharge flood coefficient in compare to corresponding staggered overflow. Investigating the ratio of input key width to the output key width show that the range of 1.25 to 1.5 has the highest rate flood coefficient. The rate of flood coefficient in overflow of piano keys is more than the overflow of rectangle staged overflow with slope cycle. Also, overally the rate of flood coefficient in the model with the only outlet slope is more than the model with inlet slope and a model combined with outlet and inlet slope. Among the various models, the rectangle staged overflow with inlet slope keys has little engative effect on the rate of flood coefficient. The results of the study indicate that using the basis makes the rate of flood coefficient increased. Using a shield wall makes the rate of flood coefficient increased. The comparison of the findings showed that the rates of flood coefficient in PKRFH model was firstly more than the rates of flood coefficient in PKRFF (crests) but by increasing Ht/p the rates of flood coefficient gets gradually closer in the two models.