FINITE DIFFERENCE OPERATORS FOR THE RANKINE SOURCE METHOD

The Rankine source method is widely used for computing free-surface potential flows past a ship. In this method a finite difference operator is used as a discrete estimate to a partial derivative, which must satisfy the numerical radiation condition at the downstream boundary. It has been found that the popular Dawson operator works well for moderate ship speeds but the results are less accurate for high and low speeds. The current paper addresses these problems by investigating possible replacements for Dawson operator. Fourteen different operators are considered as possible candidates, including two-point through five-point upstream operators. Each operator was analysed by comparing its discrete Fourier transform with the corresponding continuous Fourier transform in the wavenumber space. Several of these operators were used to calculate a two-dimensional tests case of a fully submerged source. The quality of the computed results were found to be highly dependent upon the choice of the finite difference operator. A new five-point upstream operator which performs well for cases corresponding to high speeds is introduced.

• Supplemental Notes:
  • OMAE 1992, 11th Intl Conf on Offshore Mechanics & Arctic Engng; 7-12 June 1992; Calgary, Canada. Sponsored by ASME et al. Procs. Publ by ASME. Vol 1, Pt A, p 353 [9 p, 3 ref, 2 tab, 22 fig]
• Authors:
  • Strobel, K H
  • Cheng, B H
• Publication Date: 1992

Language

• English

Subject/Index Terms

• TRT Terms: Numerical analysis; Potential flow
• Old TRIS Terms: Wave forces on ships
• Subject Areas: Marine Transportation;

Filing Info

• Accession Number: 00704677
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM