Piano Key Weirs (PKW) are novel state-of-the-art hydraulic structures that can enhance the discharging capacity of a traditional ogee-crested weir or even labyrinth weir by several times without increasing the upstream inundation. Depending upon the complexity in the geometry and flow pattern, several studies have been carried out in the past to accurately estimate the coefficient of discharge of PKWs. Application of PKWs in a diversion structure or low dam may create submerged flow during the high flood events and rise the upstream inundation level. Figure 1 shows a typical PKW configuration having three cycles or units. The CFD studies dealt previously on the head-discharge correlation of PKW were focused mainly on the free-flowing weirs. It would be highly interesting to model a submerged PKW for different submergence ratios which could minimise the experimental cost and save time. A few examples of the experimental study on submerged PKWs are Belaabed & Ouamane, (2013); Cicero & Delisle, (2013); Dabling & Tullis, (2012); Kabiri-Samani & Javaheri, (2012).
The primary objective is to develop a CFD model that can efficiently predict the coefficient of discharge of submerged PKWs under different tailwater conditions. The specific objectives would be:
Figure 1 Basic parameters of PKW with different sections (from Anderson & Tullis (2012))