ABSTRACT The problem of flow-induced vibration has been studied extensively. However, much of this research has focused on the smooth cylinder to gain an understanding of the mechanisms that cause vortex-induced vibration. In this paper results of an investigation of the effect of surface roughness on the crosswind forces are presented. Measurements of the sectional RMS fluctuating lift forces and the axial correlation of the pressures for Reynolds numbers from 1 x 10 5 to 1.4 x 10 6 are given. It was found that surface roughness significantly increased the axial correlation of the pressures to similar values found at high subcritical Reynolds numbers. There was little effect of the surface roughness on the sectional lift forces. The improved correlation of the vortex shedding means rough cylinders will be subject to larger cross-wind forces and an increased possibility of vortex-induced vibration compared to smooth cylinders. INTRODUCTION The problem of vortex-induced vibration confronts us in many everyday situations; from the vibration of a domestic television aerial to flow over heat exchanger tube banks to large towers, and in some situations left untreated can lead to structure failures. The importance of finding causes and solutions to vortex induced vibration is reflected in the quantity of research. Many of the circular cylinder applications mentioned in the previous paragraph are not highly polished, instead they have a degree of surface roughness caused by manufacturing tolerances or environmental conditions. Research on smooth cylinders in low turbulence flow has shown the fluid-structure mechanisms that result in vibration over a wide range of Reynolds numbers. However, the quantity of research data available showing the effect of surface roughness an
