Pompage d'Ekman dans un écoulement de marée : génération d'un courant résiduel

Ekman pumping in a tidal motion : generation of a rectified current

Laboratoire des Ecoulements Géophysiques et Industriels Institut de Mécanique de Grenoble, C.N.R.S., URA 1509

Abstract

Among the potential sources of suspended materials transport, tidal currents obviously play an important role : firstly due to the usual asymetry between flux and ebb (non-linearity of the tidal wave), but also because of the coastal rectification of a purely sinusoidal offshore current, which tends to the generation of a residual circulation. This process comes out from the modification of the lateral boundary layer by the " Ekman pumping ". We make a physical modelling of this motion on the large rotating tank of the Institut de Mécanique de Grenoble and study the hydrodynamic behaviour by varying the main parameters of the flow. The results of this work may be applied to the firench coasts of Pas-de-Calais, near Boulogne s/mer.