Some Recent Studies of Vortex Shedding With Application to Marine Tubulars and Risers

Many types of marine structures are susceptible to vortex-excited oscillations. These include the risers and conductor tubes that are employed in offshore drilling and production, deep water pipelines, and members of jacketed structures. Deepwater pile installation and driving operations also have been hampered by problems arising from vortex shedding. A discussion is given in this paper of the problems caused by vortex shedding from flexible, bluff cylinders in steady current flows. In particular, recent measurements of the steady and unsteady deflections caused by the vortex-excited drag and lift forces are discussed. Various approaches that have been developed for the suppression of vortex-excited oscillations are reviewed. A classification and a comparison are made of the effectiveness of several suppression devices, and some practical examples of their application are presented.