MOTION OF A CABLE USED AS A MOORING

The equations governing the motion in a vertical plane of a heavy cable in a fluid are derived and applied to the problem of determining the tension in a cable that is fixed at the bottom and given a harmonic displacement of the upper end tangent to the undeformed cable. An order of magnitude analysis reveals the existence of a boundary layer near each end within which the spacial variations of the transverse dynamic displacement compoment varies rapidly compared with the special variation outside this region. For a range of parameters in which the Froude number is negligible in comparison to the hydrodynamic drag number the temporal variation of the dynamic tension is shown to be described by a first-order, nonlinear, ordinary differential equation. This equation has been solved both numerically and analytically using the Galerkin method giving results which are in very good agreement. Finally, the numerical results are compared with experiment and shown to be in good agreement. Thus, a relatively simple formula can be used to describe this type of dynamic behavior.

• Corporate Authors:

  American Institute of Aeronautics and Astronautics

  1290 Avenue of the Americas
  New York, NY  United States  10019
• Authors:
  • Williams, H E
• Publication Date: 1975-7

Media Info

• Features: References;
• Pagination: p. 107-118
• Serial:
  • Journal of Hydronautics
  • Volume: 9
  • Issue Number: 7
  • Publisher: American Institute of Aeronautics and Astronautics

Subject/Index Terms

• TRT Terms: Cables; Drag; Dynamics; Mooring cables; Offshore moorings
• Old TRIS Terms: Cable drag; Cable dynamics
• Subject Areas: Marine Transportation; Terminals and Facilities;

Filing Info

• Accession Number: 00127590
• Record Type: Publication
• Source Agency: American Institute of Aeronautics and Astronautics
• Files: TRIS
• Created Date: Dec 3 1975 12:00AM