A DESCRIPTION OF HYDRODYNAMIC FORCES ON TENSION LEG PLATFORMS USING A MULTIVARIATE HERMITE EXPANSION

A new method is proposed for the expansion of nonlinear drag forces expressed in terms of multivariate Hermite polynomials correct up to the second-order. The viscous nonlinear drag term including the effect of instantaneous wave surface profile is decomposed into the mean (zeroth-order), viscous exciting and viscous damping terms (first-order) and the slowly varying drift force term (second-order). This decomposition permits spectral representation of the first-order viscous forces in terms of the spectral density function of the water particle velocities. The second-order viscous force can be described within the spectral framework by the spectral convolution or other related techniques involving the spectral density function of the relative fluid-structure velocities and the wave surface elevation. The present formulation in the frequency domain provides a very good agreement with the time domain simulation. The proposed analysis not only retains the important features of the nonlinear interactions in the frequency domain analysis, e.g. the spectral contents at the sum and difference frequencies, but also clearly offers accuracy comparable to the time domain approach at a fraction of the computational effort.

• Supplemental Notes:
  • OMAE 90, Proc of the 9th Intl Conference Offshore Mechanics & Arctic Engng, Houston Tx USA, 18-23 Feb 1990, v 2, pt A, p 133 [10 p, 18 ref, 2 tab, 7 fig]
• Authors:
  • Li, Yixuan
  • Kareem, A
• Publication Date: 1990

Language

• English

Subject/Index Terms

• TRT Terms: Drag; Drift; Tension
• Old TRIS Terms: Drift forces; Tension leg platforms
• Subject Areas: Geotechnology; Marine Transportation;

Filing Info

• Accession Number: 00699510
• Record Type: Publication
• Source Agency: British Maritime Technology
• Files: TRIS
• Created Date: Aug 14 1995 12:00AM