Abstract
The semisubmersible platform is one of the most important equipment for the exploitation of deep-sea oil and gas. And its survival and operational capacities depend on the towing and motion performances. The present work investigates the properties of different platform component designs based on their towing and motion performances under wind and waves by using an integrated computational fluid dynamics (CFD) method. The joint application of RANS and a VOF/6-DOF solver compiled in a new Fluent UDF Library is adopted for the main calculation. Numerical simulations and results demonstrate that the VOF/6-DOF solver is accurate and stable, which could achieve the same functions as the previous OpenFOAM scheme. In order to acquire a better towing performance, different shapes are suggested for the pontoon end shape, the column cross section, and the brace longitudinal section, respectively. As to the motion response, among all the three design selections, the column cross section has the greatest influence on the whole platform. The simulation results reveal that circle section increases the roll and pitch response and reduces the heave response, to which the square section is adverse.
Highlights
Because of their limited deployment range, fixed platforms could hardly meet the need of deep exploitation of marine source, which includes renewable energy, oil and gas, et al.; recent focus has been shifted to the floating offshore platforms, especially the semisubmersible offshore platform [1]
The effects of different structural components on the towing and motion performances are investigated by using the integrated computational fluid dynamics (CFD) method that contains Reynolds-averaged Navier–Stokes (RANS) with stress transport (SST) k-ω turbulent model, a volume of fluid (VOF)/6-DOF solver, and a User Defined Functions (UDFs) Library for reading the time series of wave speed. e numerical simulations lead to the following conclusions: (a) e VOF/6-DOF solver compiled in a new Fluent UDF Library has been validated to be accurate and stable
By comparing the heave responses of a wind turbine platform used in previous study and the production platform of Case 3 with different methods, it could be verified that the innovative solver adopted in the present study is relatively in agreement with OpenFOAM
Summary
Because of their limited deployment range, fixed platforms could hardly meet the need of deep exploitation of marine source, which includes renewable energy, oil and gas, et al.; recent focus has been shifted to the floating offshore platforms, especially the semisubmersible offshore platform [1]. Shock and Vibration incorporating the wind loading and the stochastic waves based on our previous studies [13] and [14] It was realized by integrating modules of MATLAB, ANSYS, and Fluent to investigate the motion and towing performances. A number of 6-DOF solvers have been developed over the past 20 years [16] and applied to record aircraft, ship, and submarine motions [17,18,19,20] More recently, it expands to offshore platform dynamics [21,22,23]. By compiling a VOF/6-DOF solver in a Fluent UDF Library, a tightly coupled CFD/6-DOF algorithm is constructed and used to monitor the towing resistance and motion response of a semisubmersible platform under the combined wind and wave loadings.
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