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Journal of Marine Science and Application

, Volume 17, Issue 3, pp 297–311 | Cite as

Radiation and Exciting Forces of Axisymmetric Structures with a Moonpool in Waves

Keynote Contribution for the International Workshop on Wave Loads and Motions of Ships and Offshore Structures, Harbin, China, 5-7 November, 2017
  • Ronald W. YeungEmail author
  • Lu Wang
Research Article
  • 57 Downloads

Abstract

A highly efficient “hybrid integral-equation method” for computing hydrodynamic added-mass, wave-damping, and wave-exciting force of general body geometries with a vertical axis of symmetry is presented. The hybrid method utilizes a numerical inner domain and a semi-infinite analytical outer domain separated by a vertical cylindrical matching boundary. Eigenfunction representation of velocity potential is used in the outer domain; the three-dimensional potential in the inner domain is solved using a “two-dimensional” boundary element method with ring sources and ring dipoles to exploit the body symmetry for efficiency. With proper solution matching at the common boundary, both radiation and diffraction potentials can be solved efficiently while satisfying the far-field radiation condition exactly. This method is applied to compute the hydrodynamic properties of two different body geometries: a vertical-walled moonpool with a bottom plate that restricts the opening and a spar-like structure with a diverging bottom opening inspired by designs of floating Oscillating Water Columns. The effects of the size of the bottom opening on the hydrodynamic properties of the body are investigated for both geometries. The heave motion of the floater as well as the motion of the internal free surface under incident wave excitation are computed and studied for the spar-like structure.

Keywords

Moonpool Spar Oscillating water column Potential flow Hybrid method Axisymmetric body 

Notes

Acknowledgments

Partial support for this work was provided by the American Bureau of Shipping Endowed Chair in Ocean Engineering held by the first author.

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Copyright information

© Harbin Engineering University and Springer-Verlag GmbH Germany, part of Springer Nature 2018

Authors and Affiliations

  1. 1.Department of Mechanical EngineeringUniversity of California at BerkeleyBerkeleyUSA

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