Accession Number : AD0709635

Title :   WAVE FORCES ON A CIRCULAR PILE DUE TO EDDY SHEDDING.

Descriptive Note : Technical rept.,

Corporate Author : CALIFORNIA UNIV BERKELEY HYDRAULIC ENGINEERING LAB

Personal Author(s) : Bidde,Devidas D.

Report Date : JUN 1970

Pagination or Media Count : 148

Abstract : 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 anslyses of irregular waves and lift forces using Fast Fourier Transform techniques are presented. (Author)

Descriptors :   (*FOUNDATIONS(STRUCTURES), OCEAN WAVES), (*OCEAN WAVES, FORCE(MECHANICS)), LIFT, CYLINDRICAL BODIES, MATHEMATICAL ANALYSIS, THESES

Subject Categories : Physical and Dynamic Oceanography
      Marine Engineering

Distribution Statement : APPROVED FOR PUBLIC RELEASE