Akademik Veri Yönetim Sistemi
Emerging Technologies in Fluids, Structures, and Fluid/Structure Interactions - 1999 (The ASME Pressure Vessels and Piping Conference), Boston, MA, USA, 1 - 05 Ağustos 1999, cilt.396, ss.333-341
Risers are very important parts of modern Offshore Structures used for the production of hydrocarbons. The risers systems have become more important due to the increased used of Floating Production Systems (FPS). The demand for reliability of risers and riser systems has also increased despite the ever increasing water depths and environmental harshness that the production units are exposed to. In order to optimize riser, riser system and riser bundle design it is important to be able to predict hydro dynamic loads with a high confidence level. With the present decrease in computer hardware costs and increase in computing capacity, Computational Fluid Dynamics (CFD) is starting to become a tool that can be usefully employed for the designs of these vital structures. Work by the CFD group at the University of Hertfordshire has demonstrated that using an Arbitrary Langrangian Eularian i(ALE) approach to the modelling of the cylinder (riser) motion can yield good results. Furthermore, in turbulent flows the Large Eddy Simulation (LES) of turbulent flows based on the Smagorinsky Sub-grid-scale turbulence model has been shown to yield far more realistic results than the very conservative values obtained by traditional two-equation turbulence models. In the comparison of the results from the various turbulence models it is also concluded that LES based simulations are not overly expensive in terms of computing time when compared to realistic two-equation based simulation. Present work is comparing results from two-dimensional simulations with three-dimensional results and it shows that three dimensional simulations further removes overconservatism from hydrodynamic loading values whilst giving more realistic flow field predictions.