Accession Number:

ADA030403

Title:

In-Line and Transverse Forces on Smooth and Sand-Roughened Cylinders in Oscillatory Flow at High Reynolds Numbers

Descriptive Note:

Interim rept. Feb-Jun 1976

Corporate Author:

NAVAL POSTGRADUATE SCHOOL MONTEREY CA

Personal Author(s):

Report Date:

1976-06-04

Pagination or Media Count:

72.0

Abstract:

This report presents the results of an extensive experimental investigation of the in-line and transverse forces acting on smooth and sand- roughened circular cylinders placed in oscillatory flow at Reynolds numbers up to 1,500,000, Keulegan-Carpenter numbers up to 100, and relative sand- roughnesses form 1800 to 150. The drag and inertia coefficients have been determined through the use of the Fourier analysis and the least-squares method. The transverse force lift has been analysed in terms of its maximum, semi peak-to-peak, and root-mean-square values. In addition, the frequency of vortex shedding and the Strouhal number have been determined. The results have shown that a for smooth cylinders, all of the coefficients cited above are functions of the Reynolds and Keulegan-Carpenter numbers, particularly for Reynolds numbers larger than about 20,000 b for rough cylinders, the force coefficients also depend on the relative roughness kD and differ significantly from those corresponding to the smooth cylinder and that c the use of the frequency parameter D sqnu T and the roughness Reynolds number U sub m knu allow a new interpretation of the present as well as the previously obtained data.

Subject Categories:

  • Physical and Dynamic Oceanography
  • Structural Engineering and Building Technology
  • Fluid Mechanics

Distribution Statement:

APPROVED FOR PUBLIC RELEASE