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ABSTRACT
Analyses of turbulent flows through the downstream slopes of embankment dams are important for dam safety assessments, especially considering high-risk scenarios such as a sudden release of water due to internal erosion. Flow prediction is difficult in such situations due to coarseness of construction materials and high Reynolds numbers. The present study addresses this issue through comprehensive numerical modelling. The novelty of the proposed approach lies in a combination of large-scale experiments and three-dimensional numerical simulations, leading to a fully calibrated and validated model that is applicable to flows through cobble-sized materials (100–160 mm in diameter) at high Reynolds numbers (>104). Comparing the results of the standard turbulence models to data from the large-sale experiments, the renormalization group theory-based model yielded the smallest relative errors based on the hydraulic gradients. Considering the flow field, the turbulent shear stress increased by a factor of 17, and the time-averaged vorticities intensified by factors of 2, 6 and 10 for vorticities in the x-, y- and z-directions, respectively, due to the presence of cobbles.
Acknowledgements
The authors acknowledge the anonymous reviewers and editorial board for comments that helped to improve the manuscripts, and the Flow-3D support group for providing useful suggestions on numerical issues.
Funding
This study was performed as part of a PhD programme financed by the Swedish Hydropower Centre (Svenskt Vattenkraft Centrum, SVC, http://www.svc.nu). SVC was established by the Swedish Energy Agency, Elforsk and Svenska Kraftnät, together with Luleå University of Technology (LTU), KTH Royal Institute of Technology, Chalmers University of Technology and Uppsala University.