Drag Forces on Oscillating Cylinders in a Uniform Flow

Abstract

This paper describes the drag coefficients of cylinders oscillated in both in-line and transverse directions to a uniform flow. The drag coefficients CD have been obtained experimentally over a wide range of oscillation frequencies, amplitude and flow velocities for the cylinders of various diameters under simulated practical offshore conditions. New expressions are proposed for the drag coefficients CD of an oscillating cylinder in a uniform flow. The boundary between the regions, where CD ≃1 and CD <1, is clearly established by employing the Keulegan-Carpenter number and the reduced velocity as dimensionless numbers. These dimensionless numbers also clearly describe CD variation within the region of rapid CD value decrease.