Wave forces on offshore pipelines. A total force concept

Abstract

This paper presents the results of analysis of the wave induced forces on a smooth horizontal cylinder placed near a plane boundary using a total force concept. Two formulations are used, one using the vectorial form of the Morison's equation and the other utilizing the vectorial form of the Morison's equation with the inclusion of a lift force term. In both methods the predicted force vector is fitted to the measured force vector by optimizing both the predicted magnitude and direction. The advantage of this approach is that only one set of force transfer coefficients is necessary to estimate the total force. Comparison between the predicted forces with those measured in the laboratory investigation shows that the total force model which includes the lift force term compares very satisfactorily with the measured values. The total force transfer coefficients are further evaluated and correlated with the period parameter for various clearances.