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Sand ripples and dunes

Charru, François Sand ripples and dunes. (2013) In: Complex Fluids and Flows in Industry and Nature II, 24 July 2013 - 26 July 2013 (Vancouver, Canada).

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Abstract

Sand or granular patterns emerge from erodible flat beds in a wide variety of physical environments: in water channels, rivers and coastal areas, in deserts on Earth and under methane or CO2 atmospheres on other planets, in hydraulic engineering and industrial pipe flows. These bedforms exhibit different shapes depending on the symmetries of the fluid forcing, or the boundary conditions. Their size ranges from the centimeter scale for ripples up to hundreds of meters for dunes. The dynamics of these patterns results from the interaction between the fluid flow and the bed topography through particle transport, which may take place in a thin bedload layer, or in a larger saltation layer, or as a suspension. The understanding of the formation of these sand patterns has stimulated a huge number of studies, notably since the pioneering work of Bagnold in the middle of the last century. Some important issues, still debated, are the following. What are the relevant dynamical mechanisms controlling the emergence of bedforms? Do they form by linear instability or non-linear processes like pattern-coarsening? What determines their time and length scales, so different in air and water? What are the similarities and differences between aeolian and subaqueous patterns? What is the influence of the mode of transport: bedload, saltation or suspension? Can bedforms emerge under any hydrodynamical regime, laminar and turbulent? The presentation will discuss the above issues and propose, from the recent literature, a unified description of bedform growth and evolution.

Item Type:Invited Conference
Audience (conference):International conference without published proceedings
Uncontrolled Keywords:
Institution:French research institutions > Centre National de la Recherche Scientifique - CNRS (FRANCE)
Université de Toulouse > Institut National Polytechnique de Toulouse - Toulouse INP (FRANCE)
Université de Toulouse > Université Toulouse III - Paul Sabatier - UT3 (FRANCE)
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Deposited On:18 Dec 2013 09:50

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