CFD-Based Numerical Wave Basin for Offshore Floater Design

Abstract

Technip recently has developed new cost-effective and riser-friendly Semi-submersible hull forms adapted to various operation sites, with considerable saves in design cost and time. This achievement is greatly in debt to Technip's numerical wave basin, which has been developed and validated through previous projects and collaborative R&D efforts with clients. Validation of the numerical wave basin against the model test and full-scale measurement data has proven that the numerical wave basin can provide more realistic and reliable prediction of the wave-and vortex-induced motion than the physical model test. The validated numerical wave basin has been applied to develop a new semi-submersible hull design for a given design environment, partially replacing the role of the physical model test in the traditional design spiral. The new design spiral based on numerical wave basin provides optimized hull design more expeditiously and efficiently than the traditional design spiral based on physical model test. Review of the development, current status and future prospects of numerical wave basin for offshore platform design is presented in this paper.re-calibrated to provide more accurate design parameter for the next phase of the project, which is the typical case for the design of conventional hull forms. There have been a few occasions, however, the discrepancy between prediction and model test results being beyond the adjustment of empirical formula and result into major modification of the hull design, and some cases even change of the design concepts, which lead to considerable delay and increase of project schedule and cost. This worst scenario occurs when unexpected physical phenomena that could not be modeled by the analytic model are observed in the model test. These unexpected physical phenomena are mostly related to nonlinear fluid force and viscous effects.Along with the efforts to improve conventional global performance tools, Technip has been investing in CFD capability for the analysis of viscous dominant problems such as drag coefficients of hull parts and vortex induced motion of Spars (Halkyard et al., 2006, Atluri et al, 2009, Lefevre et al., 2013. Recently, the utilization of CFD for offshore floater design extends to free-surface flow problems for Spars and multi-column floaters with the aides of the advances of CFD codes in free-surface capturing and moving mesh techniques, together with the computing power of modern high-performance parallel computers that has been growing exponentially year by year. Technip is developing numerical wave basin to provide design parameters of run up, air gap, green water and nonlinear wave load on the hull at the early stage of floater design. The numerical wave basin provides wave-induced loads and motion on fixed and floating structures correlating with the model test measurements within engineering tolerance for the design purpose , Wu et al., 2014. Numerical wave basin will gradually substitute the role of scaled model test in the design spiral, as depicted in ...

Prediction of Deepwater FPSO responses using different numerical analysis methods

“…Additionally, numerical simulations may reduce the amount of cost as well as time in manufacturing a physical system. Technip has recently modified their design process via the development of a numerical wave basin [4]. This was built on the features provided by the commercial software STAR-CCM+, and coupled with their in-house program to improve certain functionalities that was yet fully developed.…”