Numerical Study on Geometrical Configurations of Perforated Cylindrical Structures under Regular Waves

Abstract

Offshore tension leg platforms (TLPs) is often subjected to critical environmental loads that cause serious damage; Mars TLP in Gulf of Mexico, damaged by hurricane Katrina in the year 2005 is an example. Existence of external perforated cover reduces hydrodynamic forces on the existing members caused by direct wave impact. Although many studies confirm this fact but variations in the water particle kinematics along the water depth needs a detailed investigation to verify the phenomenon. Geometric configuration of the column member of the damaged MARS TLP is modeled on a 1:100 scale with an external perforated cover. Variations of water particle kinematics of the column member encompassed by perforated cover are presented through detailed computational fluid dynamics (CFD) analysis. Traces of the horizontal water particle velocity along the water depth are derived for a wide range of sea states for various chosen geometric configuration. Results of the numerical studies show that there is a significant reduction in the water particle velocity, which verifies the fact of reduction in forces on the column members. The research reported in this paper has a direct application in the repair of damaged column members by encompassing with outer perforated cover.