Caractérisation d'effets de sillages rencontrés en milieu offshore

The interactions between several cylinders placed in close proximity are the subject of many studies, because of the strong repeated loads that they create on these structures. For flexible or mobile structures, the wake effects can produce large amplitudes motions. These displacements can be higher than those considered during the lock-in of a single cylinder, to reach several diameters. Depending the initial spacing, they lead sometimes to clashes with potentially high intensity, between the cylinders. To better understand these phenomena, an experimental study was carried out, bearing on the interaction between two models of tensioning buoy supporting hybrid risers. After checking that the models used were able to correctly reproduce the movements induced by the VIV on a single cylinder, the response of two cylinders in tandem arrangement was studied. This article presents a study of the phases of clashes which were observed for several initial spacing.