Vortex-Induced-Vibration of jack-ups with cylindrical legs in multiple modes

Abstract

A simple mathematical model was developed based on the single-degree-of-freedom analogy and principle of conservation of energy evaluating various modes of Vortex-Induced-Vibration (VIV) of a jack-up with cylindrical legs in steady flow. Mass ratio, damping ratio and mode factor were found to be the important parameters controlling the inline and cross flow VIV and radius of gyration for the yaw VIV. Criteria for the initiation of the three VIV modes were developed for the cases of a single 2D cylinder, four rigidly coupled 2D cylinders in rectangular configuration and a jack-up experiencing