Numerical modeling to develop strake design of Spar platform for Vortex-Induced motions suppression

Abstract

In this paper, a numerical study was performed aiming to reduce the Spar hull surge and sway response due to marine currents for various arrangements of strakes. Spar is a compliant platform consisting of a large-diameter single-cylinder, supporting a deck, moored in place vertically. Spar Vortex-Induced Motions (VIM) suppression is one of the most challenging offshore industries for assessing mooring, risers, and structure fatigue. This phenomenon is mostly occurring due to the interaction of marine currents with Spar platforms. Therefore, Spar VIM response has been the subject and focus of some research in the past few decades. In this research, the interaction of the marine current with a Spar model was numerically simulated. The results were compared with the VIM response of the existing Spars with conventional strake design to validate the model. Different strake patterns and a conventional bare hull Spar armed with strakes (Base model) were used to model the VIM response of the platform. The results demonstrated the possibility of Spar VIM response reduction due to the improving design of Spar strakes. Eventually, the best model was proposed with 58% suppression in sway motion and 9% in surge motion of VIM response and the results were discussed.