Oscillatory loads on circular cylinder with secondary structures

Thor Ugelvig Petersen, Xerxes Mandviwalla, Erik Damgaard Christensen*, Niels Jacob Tarp-Johansen, Finn Rüdinger

*Corresponding author for this work

Research output: Contribution to journalJournal articleResearchpeer-review


This study deals with a numerical and experimental study of the secondary structures effect on the load on the main circular cylinder. Its objective is to address the increasing amount of offshore structures installed as part of offshore wind farms. The typical support structure for a wind turbine is a monopile foundation. Boat-landings are attached to the monopile and these structures act as secondary structures. Forces on a cylinder with and without secondary structures attached in unsteady flows have been measured experimentally and simulated numerically. The results of the tests were compared to each other and to existing work in the present report for validation of the CFD model. The secondary structures were represented by circular cylinders placed at different orientations around the main circular cylinder. All the analyses assumed uniform conditions transverse to the flow direction (i.e. 2D set-up). The numerical simulations were based on the OpenFOAM CFD tools. The validation tests with a circular cylinder without secondary structures showed good agreement between the physical and numerical results, as well as to the results available in the open literature. The orientation of the secondary structures had a clear influence on the drag related part of the force as the drag coefficient when the secondary structure was orientated towards = 90°, i.e. perpendicular to the flow direction. The inertia part of the force, i.e. the inertia force coefficient , was only affected by the orientation to small extend.
Original languageEnglish
Article number102935
JournalJournal of Fluids and Structures
Number of pages22
Publication statusPublished - 2020

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