Print Email Facebook Twitter Drag forces on oscillating cylinders Title Drag forces on oscillating cylinders Author Van Hazendonk, H.C. Sluis, C.M. Contributor Battjes, J.A. (mentor) Dijkman, M.W.J.W. (mentor) Anaturk, A.R. (mentor) Tromans, P.S. (mentor) Faculty Civil Engineering and Geosciences Department Hydraulic Engineering Date 1988-11-01 Abstract This report is the result of graduate work done at the Shell Laboratory, KSEPL, Rijswijk, to finish the study in Civil Engineering at the Technical University of Delft. A theoretical and experimental study has been made of drag forces on cylinders, which are oscillating at relatively large beta-numbers and small K-numbers. Drag forces are important, since they control the dynamic response and thus influence the fatigue life of offshore structures. First, the theory on drag forces on circular cylinders has been studied. Until now, there was only an analytical expression for the drag force in case of a completely laminar attached boundary-layer around the cylinder, the Stokes' solution. Further, there is the empirical Morison equation which can be used to calculate drag forces for all kinds of flow fields around the cylinder. To use this equation however, experimental data are needed. In this study, a model has been developed with which drag forces on circular cylinders can be calculated, no matter whether the boundarylayer is laminar or turbulent or both, as long as it remains attached to the cylinder. The model is applicable to smooth and rough cylinders. Further, in the past there has been very little experimental research on this subject, and therefore a test-facility has been built at KSEPL. Some experiments have been done with the facility in the regime in which the theory is valid, using a smooth, circular cylinder. These experiments show that Stokes' expression for the drag force, valid for a laminar boundarylayer, considerably underestimates the drag in the turbulent, attached flow regime. The experiments also indicate possible future improvements to the facility. Comparison of theoretical and experimental results shows that the present model predicts the forces very weIl in the attached flow regime at all K- and beta-numbers. Subject KSEPLdrag forcesoscillating cylinders To reference this document use: http://resolver.tudelft.nl/uuid:737be67e-58df-470e-ade9-8da371107710 Part of collection Student theses Document type master thesis Rights (c) 1988 Hazendonk, H.C.Sluis, C.M. Files PDF Hazendonk1988a.pdf 23.4 MB PDF Hazendonk1988b.pdf 5.69 MB Close viewer /islandora/object/uuid:737be67e-58df-470e-ade9-8da371107710/datastream/OBJ1/view