Fluvial and submarine morphodynamics of laminar and near‐laminar flows: a synthesis |
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| Authors: | ERIC LAJEUNESSE LUCE MALVERTI PIERRE LANCIEN LAWRENCE ARMSTRONG FRANCOIS MÉTIVIER STEPHEN COLEMAN CHARLES E SMITH TIMOTHY DAVIES ALESSANDRO CANTELLI GARY PARKER |
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| Institution: | 1. Equipe de Dynamique des Fluides Géologiques, Institut de Physique du Globe de Paris, Paris, France (E‐mail: lajeunes@ipgp.jussieu.fr);2. Department of Civil & Environmental Engineering, The University of Auckland, Auckland, New Zealand;3. Department of Mechanical Engineering, Virginia Tech University, Blacksburg, VA 24060, USA;4. Department of Geological Sciences, University of Canterbury, Christchurch, New Zealand;5. Department of Civil & Environmental Engineering and Department of Geology, University of Illinois, Urbana, IL 61801, USA |
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| Abstract: | The interaction of flow with an erodible bed in alluvial rivers and deep‐sea channels gives rise to a wide range of self‐formed morphologies, including channels, ripples, dunes, antidunes, alternate bars, multiple‐row bars, meandering and braiding. As the flow is invariably turbulent in field manifestations of these morphologies, there has been a tendency to assume that turbulence is necessary for them to form. While turbulence undoubtedly has an important influence when it is present, it is not necessary for any of these features. Indeed, all of these features can be formed by the morphodynamic interaction of purely laminar or nearly laminar flow with an erodible bed. This paper provides a survey and synthesis of a wide range of laminar or near‐laminar flow analogues of morphologies observed in the field. Laminar‐flow analogues of turbulent‐flow morphologies cannot and should not be expected to satisfy dynamic similarity in terms of all relevant dimensionless parameters. What is of more significance is the convergence of the underlying physics. It is illustrated in this paper that many existing theoretical frameworks for the explanation of turbulent‐flow morphodynamics require only relatively minor modification in order to adapt them to laminar flows. |
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| Keywords: | Fluvial and submarine morphodynamics laminar flow microscale modelling river bedform turbulent flow |
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