A study of turbulent flow in large-scale porous media at high Reynolds numbers. Part II: flow physics

ABSTRACT

The evaluation of hydraulic performance of coarse porous media at high Reynolds numbers is of significant importance for dam safety assessment. To address this task, the present study uses a numerical approach based on a rigorous theoretical framework. The novelty of the study lies in the application of a fully calibrated and validated numerical three-dimensional model and a set of modified equations for momentum transfer and the associated coefficients for flow in porous media. A Lagrangian particle tracking model was used to estimate the lengths of the flow channels that developed in the porous media. Gamma distributions were fitted to the normalized channel lengths, and the scale and shape parameters of the gamma distribution were found to be Reynolds number dependent. These shape parameters can be estimated from the suggested polynomial equations. The proposed normalized length parameter can be used to evaluate permeability, energy dissipation, induced forces, and diffusion. It was found that shear forces exerted on the coarse particles depend on the inertial forces of the flow and can be estimated using the proposed equation for the developed turbulent flows in porous media.

Keywords:

• Numerical experimentation
• particle tracking
• porous-media flow
• shear turbulence
• wall-bounded flows

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.

Additional information

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.