Roughness Effect on Viscous Forces Acting on an Oscillating Circular Cylinder

Abstract

Roughness effect by marine growth is one of the most important factors in estimation of wave loads on offshore structures. Most researches on viscous forces acting on oscillating roughened cylinders focus the attention on the relative roughness height K/D which is the ratio of the roughness height (K) to the cylinder diameter (D). In the present study, viscous forces acting on oscillating 10 different roughened cylinders are experimentally investigated. The relation between the relative roughness height and the boundary layer thickness calculated by an oscillating boundary layer theory are also investigated.