FOURIER-KOCHIN REPRESENTATION OF FREE-SURFACE FLOWS

A recently developed theoretical formulation of wave diffraction- radiation by ships or offshore structures, motivated by the practical and theoretical importance of free-surface potential flows and the considerable complexities of existing calculation methods based on free-surface Green functions is summarized. The formulation is called the Fourier-Kochin (FK) theory. The potential flow due to a ship advancing at constant speed along a straight path through regular waves in deep water is considered. The flow due to the ship is expressed as the sum of the steady flow about the ship advancing in calm water and the time-harmonic flow associated with the incoming and diffracted-radiated waves. Thus, a frequency-domain analysis is considered. In addition, the steady ship waves the time- harmonic diffracted-radiated waves are analyzed within the classical linear potential-flow theory based on a free-surface boundary condition linearized about the uniform stream opposing the forward speed os the ship, and the free-surface Green function satisfying this linearized free-surface condition is used. The special case of wave diffraction-radiation without mean forward speed is also considered. The FK theory of wave diffraction-radiation by ships or offshore structures is expounded in Noblesse and Yang (1995), Noblesse and Chen (1996) and Noblesse and Yang (1996) which are identified at [FK1], [FK2] and [FK3]. These three basic studies also contain illustrative applications of the FK theory to the numerical evaluation of influence coefficients [FK1], the Green function of wave diffraction- radiation by an offshore structure in a current [FK2], and the representation of steady ship waves and of waves generated by an offshore structure [FK3]. The fundamental ideas and results underlying the FK theory of wave diffraction-radiation by ships or offshore structures expounded in the three studies are briefly summarized. The FK theory is based on a Fourier representation of free-surface effects. This essential aspect of the theory is examined first.

• Supplemental Notes:
  • Colloquium on Advances in Ship and Offshore Engng; 21 March 1996, Hamburg, Germany. Pprs. Publ by Institut fur Schiffbau der Universitat Hamburg, rpt 561, Feb 1996, ISBN 0- 89220-561-2, p 2 [8 p, 8 ref]
• Authors:
  • Noblesse, F
  • Yang, Chenxuan
  • Chen
  • X-B
• Publication Date: 1996

Language

• English

Subject/Index Terms

• TRT Terms: Diffraction; Fourier analysis; Free surface; Potential flow
• Old TRIS Terms: Wave diffraction; Wave radiation
• Subject Areas: Marine Transportation;

Filing Info

• Accession Number: 00728025
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Nov 4 1996 12:00AM