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Numerical Uncertainty of Piano Key Weir Discharge Coefficient Estimations by Means of 3D CFD Modelling-a Preliminary Study

Author(s): F. L. Bremer; M. Oertel

Linked Author(s): Mario Oertel

Keywords: Piano Key Weir; Numerical modelling; Mesh quality; Grid convergence index

Abstract: Since the first Piano Key Weir (PKW) was built at Goulours Dam in France in 2006 by Electricitede France, their importance as a flood release structure for gravity dams or as implementation in river systems has increased significantly. PKWs are a result of a consequent development from labyrinth weirs. In 1998, the first studies with preliminary geometries were performed in France and improved by Blanc and Lemperiere (2001). Due to the nonlinear shape, the PKW’s specific discharge was–compared to linear weirs–majorly increased, since the effective overflow length will be increased. In the past, a lot of research in terms of physical modeling, Computational Fluid Dynamics (CFD) studies or research in prototype scale were carried out. Numerical investigations can provide important knowledge of flow parameters and provide a cost-effective tool to investigate numerous PKW designs. Although a lot of numerical PKW simulations have been carried out, additional in-depth research is still needed. For numerical simulations, the mesh dependence is a major criterion with a large influence on the result quality in respect to water surface levels or flow velocities. The present paper deals with the mesh dependence related to PKW discharge coefficients. It will provide recommendations for numerical PKW simulations by investigating sufficient maximum mesh sizes with the Grid Convergence Method (GCI).


Year: 2018

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