title: Formation of localized sand patterns downstream from a vertical cylinder under steady flows: Experimental and theoretical study.
abstract: The generation of localized, spatially periodic patterns on a sandy bottom is experimentally and theoretically studied. Tests are performed in a hydrodynamic flume where patterns are produced downstream from a vertical cylinder under a steady current. It is found that patterns appear as a result of a subcritical instability of the water-sand bottom interface. A dependence of the area shape occupied by the patterns on the flow velocity and the cylinder diameter is investigated. It is shown that the patterns' characteristics can be explained using the Swift-Hohenberg equation. Numerical simulations point out that for a correct description of the patterns, an additional term which takes into account the impact of vortices on the sandy bottom in the wake of a cylinder must be added in the Swift-Hohenberg equation.
authors.affiliation: Laboratoire Ondes et Milieux Complexes, Université Le Havre Normandie, UMR CNRS 6294, 76600 Le Havre, France.
authors.forename: Anthony
authors.initials: A
authors.lastname: Auzerais
authors.affiliation: Laboratoire Ondes et Milieux Complexes, Université Le Havre Normandie, UMR CNRS 6294, 76600 Le Havre, France.
authors.forename: Armelle
authors.initials: A
authors.lastname: Jarno
authors.affiliation: Laboratoire Morphodynamique Continentale et Côtière, Université Caen Normandie, UMR CNRS 6143, 14000 Caen, France.
authors.forename: Alexander
authors.initials: A
authors.lastname: Ezersky
authors.affiliation: Laboratoire Ondes et Milieux Complexes, Université Le Havre Normandie, UMR CNRS 6294, 76600 Le Havre, France.
authors.forename: François
authors.initials: F
authors.lastname: Marin