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Slow drift of a floating cylinder in narrow-banded beam seas

Published online by Cambridge University Press:  21 April 2006

Yehuda Agnon ,
Hang S. Choi  and
Chiang C. Mei
Yehuda Agnon
Affiliation:
Woods Hole Oceanographic Institution, MA 02543, USA
Hang S. Choi
Affiliation:
Seoul National University, Seoul 131 Korea
Chiang C. Mei
Affiliation:
Massachusetts Institute of Technology, Cambridge, MA 02139, USA
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Abstract

For a long cylinder floating on the sea surface, incident sea waves with a narrow frequency band excite body oscillations of short and long periods. Depending on the stiffness of the mooring system, the body displacement of the long-period motion can be comparable with, or even greater than that of the short-period oscillations. By combining the asymptotic methods of multiple scales and inner and outer expansions, we describe an essentially analytical theory for slow sway of both small and large amplitudes. Besides showing results for various quasi-steady and transient incident waves for a rectangular cylinder, we examine the effect of the gap between the keel of the body and the sea bottom. It is found in particular that a small gap can enhance moderate resonance by blocking the flow due to long waves and increase the apparent mass of the cylinder. Real-fluid effects are not included.

Type
Research Article
Information
Journal of Fluid Mechanics , Volume 190 , May 1988 , pp. 141 - 163
Copyright
© 1988 Cambridge University Press

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References

Agnon, Y. 1986 Nonlinear diffraction of ocean gravity waves. Sc.D. thesis, WHOI-MIT Joint Program.
Agnon, Y. & Mei, C. C. 1985 Slow drift motion of a two-dimensional block in beam seas. J. Fluid Mech. 151, 279–294.Google Scholar
Beck, R. & Tuck, E. O. 1972 Computation of shallow water ship motions. Proc. Symp. on Naval Hydrodynamics, Paris (ed. R. Brard & A. Castera), pp. 1543–1587. Office of Naval Research.
Flagg, C. N. & Newman, J. N. 1971 Sway added-mass coefficients for rectangular profiles in shallow water. J. Ship Res. 15, 257–267.Google Scholar
Huijsmans, R. H. M. & Hermans, A. J. 1985 A fast algorithm for computation of 3-D ship motions at moderate forward speed. Fifth Intl Conf. on Numerical Ship Hydrodynamics. David Taylor Model Basin.
Grue, J. & Palm, E. 1985 Wave radiation and wave diffraction from a submerged body in a uniform current. J. Fluid Mech. 151, 257–278.Google Scholar
Longuet-Higgins, M. S. 1977 The mean forces exerted by waves on floating or submerged bodies, with applications to sand bars and wave-power machines. Proc. R. Soc. Lond. A 352, 463–480.Google Scholar
Maruo, H. 1960 The drift of a body floating on waves. J. Ship Res. 4, 1–10.Google Scholar
Mei, C. C. 1983 The Applied Dynamics of Ocean Surface Waves. Wiley-Interscience.
Molin, B. & Bureau, G. 1980 A simulation model for the dynamic behaviour of tankers moored to single point moorings. Intl Symp. on Ocean Engineering & Ship Handling. Swedish Maritime Research Center, Gothenburg.
Newman, J. N. 1967 The drift force and moment on ships in waves. J. Ship Res. 11, 51–60.Google Scholar
Newman, J. N. 1974 Second order, slowly varying forces on vessels in irregular waves. Proc. Intl. Symp. on the Dynamics of Marine Vehicles and Offshore Structures in Waves, University College, London (ed. R. F. D. Bishop & W. G. Price), pp. 182–186. Inst. Mech. Engrs.
Ogilvie, T. F. 1983 Second-order hydrodynamic effects on ocean platforms. Proc. Intl Workshop on Ship and Platform Motions, University of California at Berkeley (ed. R. W. Yeung). University of California.
Pinkster, J. A. 1976 Low frequency second order wave exciting forces on floating structures. Netherlands Ship Model Basin, Publ. No. 650.
Triantafyllou, M. S. 1982 A consistent hydrodynamic theory for moored and positioned vessels. J. Ship Res. 26, 97–105.Google Scholar