Wave and current forces on a vertical cylinder free to surge and sway

The problem of a vertical circular cylinder submitted to both regular waves and moderate current in water of finite depth is considered. The cylinder is free to move in surge and sway at the frequency of the incoming waves. First-order and steady second-order forces are calculated. In the calculation of mean drift forces and wave drift damping coefficients, both near-field and far-field methods are used and compared with numerical results provided by Grue [Personal communication (1993)], and with those obtained by a simple formula for wave drift damping [Aranha, J. A. P., A formula for wave damping in the drift of a floating body, J. Fluid Mech., 275 (1994) 147-155; Clark, P. J., Malenica, Š., & Molin, B., An heuristic approach to wave drift damping, Appl. Ocean Res., 15 (1993) 53-55. The method used for the calculation of the potentials is semi-analytical and based on eigenfunction expansions. © 1995.