0

Full Content is available to subscribers

Subscribe/Learn More  >

Numerical Simulations of the Flow Around Flexible Cylinders

[+] Author Affiliations
Cassio T. Yamamoto, Rodrigo A. Fregonesi, Julio R. Meneghini, Fabio Saltara

University of São Paulo, São Paulo, SP, Brazil

Paper No. OMAE2002-28154, pp. 313-320; 8 pages
doi:10.1115/OMAE2002-28154
From:
  • ASME 2002 21st International Conference on Offshore Mechanics and Arctic Engineering
  • 21st International Conference on Offshore Mechanics and Arctic Engineering, Volume 1
  • Oslo, Norway, June 23–28, 2002
  • Conference Sponsors: Ocean, Offshore, and Arctic Engineering Division
  • ISBN: 0-7918-3611-8 | eISBN: 0-7918-3599-5
  • Copyright © 2002 by ASME

abstract

In the offshore industry fluids are conveyed from the seabed to the platform through slender structures named risers. These risers are subject to shear and oscillatory flows due to currents and waves respectively, flows with a very high degree of complexity, with changes of intensity and direction the deeper the water depth. The main purpose of this work is to investigate the hydroelastic interactions which take place between flexible cylinders and fluid forces. The cylinders are subject to uniform flow, and the hydrodynamic forces are estimated by CFD, in a quasi three-dimensional fashion. This article presents the results of an investigation being carried out at the University of São Paulo and sponsored by the Brazilian Oil Company Petrobras. In this research a discrete vortex method is used to simulate the flow around a flexible cylinder. A description of this method can be found at Yamamoto et al. (OMAE 2001). A finite element structural model based on the Euler-Bernoulli beam theory was developed. In order to evaluate the dynamic response, a general equation of motion is solved through a numerical integration scheme in the time domain. The hydrodynamic forces are evaluated in two-dimensional strips. The technique used is the Discrete Vortex Method, which is a Lagrangian numerical scheme to simulate an incompressible and viscous fluid flow. The calculations are compared with experiments of a cantilever flexible cylinder immersed in a current, see Fujarra [6]. The reduced velocity vs. non-dimensional amplitude curve obtained in our calculations is compared with the experimental results. Visualizations of the wake indicate a hybrid mode of vortex shedding along the span. A 2S mode is found in regions of low amplitudes, changing to a 2P mode in the regions o larger amplitudes. The position of the transition of the modes varies with the reduced velocity. A practical case of marine risers is also presented. In this case the results for various uniform currents acting on a single, flexible cylinder, representing a riser of 120m with 100m under water, are shown. Envelopes of maximum and minimum in-line and transverse displacements are presented.

Copyright © 2002 by ASME

Figures

Tables

Interactive Graphics

Video

Country-Specific Mortality and Growth Failure in Infancy and Yound Children and Association With Material Stature

Use interactive graphics and maps to view and sort country-specific infant and early dhildhood mortality and growth failure data and their association with maternal

NOTE:
Citing articles are presented as examples only. In non-demo SCM6 implementation, integration with CrossRef’s "Cited By" API will populate this tab (http://www.crossref.org/citedby.html).

Some tools below are only available to our subscribers or users with an online account.

Related Content

Customize your page view by dragging and repositioning the boxes below.

Related eBook Content
Topic Collections

Sorry! You do not have access to this content. For assistance or to subscribe, please contact us:

  • TELEPHONE: 1-800-843-2763 (Toll-free in the USA)
  • EMAIL: asmedigitalcollection@asme.org
Sign In