67th Annual Meeting of the APS Division of Fluid Dynamics (November 23, 2014 — November 25, 2014)

V0005: Sand waves in turbulent flows

Authors

• Ali Khosronejad, St. Anthony Falls Lab, University of Minnesota
• Konstantinos Kochilas, St. Anthony Falls Lab, University of Minnesota
• Fotis Sotiropoulos, St. Anthony Falls Lab, University of Minnesota

DOI: https://doi.org/10.1103/APS.DFD.2014.GFM.V0005

In fluvial and coastal environments, sediment transport processes induced by the turbulent water flow developing over a mobile sediment bed result in the formation of sand waves (or bed forms), which grow and migrate continuously. Sand waves in nature can range in scale from millimeter-size ripples to few-meter scale mega dunes in large rivers and coastal areas and provide the primary mechanism for transporting large amounts of sediment during flooding events.  They can thus have a profound impact on the morphology, streambank stability, and ecology of waterways and also undermine transportation infrastructure such as bridges and roadways.  This video presents the results of a coupled, hydro-morphodynamic large-eddy simulation (LES) of turbulent flow in a straight open channel with a mobile sand bed.  The simulations are able to resolve all stages of sand wave formation, from small marks on the initially flat sand bed to fully grown three-dimensional dunes, and elucidate the effects of sand waves on the turbulent flow within the channel and at the water surface.  The computational method we employ in this video can be extended to develop a powerful framework for simulating sand waves during flooding events enabling us to assess and mitigate the risk to infrastructure and waterway stability.