OPEN BOUNDARY SCHEME FOR NONLINEAR IRREGULAR WAVES

In this paper, the authors propose a numerical method for the absorption of all outgoing nonlinear waves at a moving open boundary and a modified time-stepping technique for tracing particles of a material distributed on the free-surface. The basis of these methods is the mixed Euler-Lagrange description. A control parameter, the beta-value, is introduced to control the lateral movement of nodal points on the moving free surface as prescribed by the Lagrangian description. It is shown that the beta-value does not affect the free surface profiles but does affect the trajectory of the nodal points on the free surface. The application of the beta-value to the moving boundary is useful in evaluating the average mass transport, and is also valuable in terms of dealing with the nonlinear interaction between the free surface and the large-amplitude motion of floating bodies. Our open boundary scheme is based on an extension of the Orlanski boundary condition. The crucial factor in this scheme is determining the time-dependent phase velocity on the moving open boundary. We examine the stability of our open boundary scheme by changing the prediction points on the free surface near the open boundary. The trajectory of the water particles and the average mass transport as calculated by our numerical model agree well with the 2nd-order Stokes wave. It is demonstrated that nonlinear irregular waves can pass through the moving open boundary without significant reflection, and this is confirmed by comparing the generated wave profiles for two different wave flume lengths.

  • 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 345 [7 p, 11 ref, 12 fig]
  • Authors:
    • Tanaka, Y
    • Nakamura, T
  • Publication Date: 1992

Language

  • English

Subject/Index Terms

Filing Info

  • Accession Number: 00716186
  • Record Type: Publication
  • Source Agency: British Maritime Technology
  • Files: TRIS
  • Created Date: Feb 28 1996 12:00AM