Forces on roughened cylinders in harmonic flow at high Reynolds numbers.

Abstract

The in-line forces acting on sand-roughened circular cylinders immersed in an harmonically oscillating flow have been measured using a U-shaped water tunnel. The drag and the inertia coefficients have been determined through the use of a Fourier analysis. These coefficients were found to depend on the Keulegan-Carpenter number, Reynolds number, and the relative roughness. The results have shown that roughness dramatically increases the transcritical drag coefficient. It is recommended that the experiments be extended to the self-excited hydroelastic oscillations of cylinders in harmonic flows as well as the problems related to wave slamming.