Comparing the Behavior Hydrodynamics Flow Over of Type A, B, and C Piano Key Weirs

The piano key weir (PKW) is a new type of hydraulic structure that has been of great interest to designers in recent years. In the present study, steady flow on the types A, B, and C PKWs was studied numerically using the FLOW-3D numerical model. Upon software validation using the experimental data, the 3D flow pattern on the types A, B, and C PKWs was studied, and along with the evaluation of the flow hydrodynamics, the differences in the flow behavior for different geometries were explained. The results showed that the wetted perimeter of the type B PKW was more than that in the types A and C PKWs. Therefore, the velocity of the approaching flow to the type A PKW was less than that in the other two types, which led to a more uniform flow distribution over different parts of the output key and hence, decreased the local submergence and increased the outflow percent from the output key crest. This finally led to an increase in the total output discharge as well as the discharge coefficient of the type B PKW compared to types A and C PKWs.