A study of turbulent flow in large-scale porous media at high Reynolds numbers. Part I: numerical validation

• Published in: Journal of hydraulic research 2016-11, Vol.54 (6), p.663-677
• Main Authors: Ferdos, Farzad, Dargahi, Bijan
• Format: Article
• Language: English
• Subjects: Byggvetenskap; CFD validation; Civil and Architectural Engineering; high Reynolds number turbulence; laboratory studies; numerical turbulence models; Porous materials; porous media flow; Reynolds number; Turbulence models
• ISSN: 0022-1686; 1814-2079; 1814-2079
• DOI: 10.1080/00221686.2016.1211184

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 (>10 4 ). 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.