WAVE FORCES ON A CIRCULAR PILE DUE TO EDDY SHEDDING

Ocean waves exert lift ( i.e., transverse ) forces on piles under some circumstances in addition to the longitudinal forces. The lift forces are related to the formation and shedding of eddies. The report describes the results of a hydraulic laboratory study to establish the conditions under which the lift forces achieve significant magnitude compared to longitudinal forces. The lift forces were found to be as great as 60% of the longitudinal forces. The Keulegan-Carpenter number is found to be a reasonable parameter to determine the regime in which eddies form, and to be related to the ratio of the lift to longitudinal forces. Eddies form in the lee of a vertical cylindrical pile subject to water waves when the Keulegan-Carpenter number has a value of about 3. For higher Keulegan- Carpenter numbers two eddies are developed and shed and the lift force is more or less regular with a frequency twice the frequency of the waves. For further increase in the Keulegan-Carpenter number turbulence develops and the lift forces show a random pattern. The ratio of the lift to the longitudinal forces appears to be at a maximum for a Keulegan-Carpenter number of about 15. Results of spectral analyses of irregular waves and lift forces using Fast Fourier Transform techniques are presented. ( Author )

  • Corporate Authors:

    University of California, Berkeley

    Berkeley, CA  USA  94720
  • Authors:
    • Bidde, Devidas D
  • Publication Date: 1970-6

Media Info

  • Pagination: 148 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00007555
  • Record Type: Publication
  • Source Agency: National Technical Information Service
  • Report/Paper Numbers: PHd
  • Files: TRIS
  • Created Date: Dec 30 1972 12:00AM