Hydrodynamic Analysis of Wave Slamming on a Horizontal Circular Cylinder

Abstract

Information about the forces acting on cylindrical structures subjected to wave impact is of significant importance in ocean engineering and naval architecture. The design of structures that must survive in a wave environment depends on knowledge of the forces that occur at impact. Impact loads due to wave slamming on horizontal members of an offshore structure are of considerable interest in the context of offshore design, particularly because such loads can give rise to structural failure. Predictions of the wave slamming force generally involve the use of a slamming coefficient. The purpose of this thesis is to analyse the wave impact forces acting on a fixed, slender, horizontal circular cylinder in the vicinity of the free surface, taking account of the intermittent submergence and wave slamming. It presents a new mathematical model for the impact forces acting on a horizontal circular cylinder from the instant of impact to full immersion. Two new expressions are derived for the slamming coefficient, the first expression as a function of the Froude number and the second expression as a function of the Keulegan-Carpenter number. A computer program is developed on the basis of the aforesaid theoretical analysis. The program is written in Fortran 90/95 and executed on the personal computer. The computational results are plotted to show the variation of the slamming coefficient with the Froude number, Keulegan-Carpenter number, wave amplitude, cylinder diameter, depth of cylinder immersion, instantaneous height of the wave surface above the mean water level and the added mass per unit length of the cylinder. In order to check the validity of the mathematical model developed, the present results are compared with the theoretical and experimental results of other investigators.