Computational and experimental investigation of scour past laboratory models of stream restoration rock structures

Ali Khosronejad, Craig Hill, Seokkoo Kang, Fotis Sotiropoulos

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Abstract

Local scour of the streambed around three models of stream restoration rock structures, including a rock vane, a cross vane, and a J-hook vane, is investigated via laboratory experiments and numerical simulations. In the experimental study, a physical model of each rock structure is constructed via an assembly of rocks and installed in a straight mobile sand bed flume. Continuous bed topography measurements provide insight into the time evolution of the scour patterns downstream of the structures and yield comprehensive data sets for validating the numerical simulations in terms of scour patterns, maximum scour depths, and bar migration dynamics. The numerical simulations are carried out using the coupled, hydro-morphodynamic Curvilinear Immersed Boundary (CURVIB) method of Khosronejad et al. (2011) [17]. The mobile channel bed and the individual rocks comprising a stream restoration structure are discretized with an unstructured triangular mesh and treated as sharp-interface immersed boundaries embedded in the background curvilinear mesh used to discretize the flow domain. For each case, simulations are carried out solving both the unsteady Reynolds-averaged Navier-Stokes (URANS) equations closed with the k-ω model and filtered Large-Eddy Simulation (LES) equations closed with the dynamic Smagorinski subgrid scale model. Both the URANS and LES models yield flow and scour patterns in reasonable agreement with the measurements with the LES results being consistently in better overall agreement with the measurements. To our knowledge, the present study is the first attempt to simulate local scour patterns around realistic model of stream restoration rock structures by taking into account and directly modeling their arbitrarily complex geometrical features.

Original languageEnglish (US)
Pages (from-to)191-207
Number of pages17
JournalAdvances in Water Resources
Volume54
DOIs
StatePublished - Apr 2013

Bibliographical note

Funding Information:
This work was supported by NSF Grants EAR-0120914 (as part of the National Center for Earth-Surface Dynamics) and EAR-0738726, National Cooperative Highway Research Program Grant NCHRP-HR 24-33 , and a Grant from Yonsei University, South Korea, as part of the ECORIVER21 project. Computational resources were provided by the University of Minnesota Supercomputing Institute.

Keywords

  • Cross vane
  • J-hook
  • Local scour
  • Numerical modeling
  • Rock vane

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