Methodology of Simulating Spread-Moored FPSO Green Water Using CFD-Based Numerical Wave Basin

Abstract

This paper presents the methodology of simulating green water events of a spread-moored FPSO platform using a CFD-based Numerical Wave Basin (NWB) with an optimized CFD model. Previous work done on the assessment of the motions of the spread-moored FPSO platform in irregular waves has demonstrated excellent agreement between CFD calculation and model test measurement (Baquet et al., 2019). This study further investigates the CFD methodology to efficiently simulate highly non-linear/breaking waves to extend the NWB applications to include prediction of green water occurrence on FPSO platforms. In this study, a CFD model is developed to enable efficient and direct simulation of green water events identified from global motion analysis of the FPSO platform. Smaller time-steps are used, and mesh refinement is applied at the regions which are potentially subjected to green water to ensure more accurate prediction of the green water elevations could be achieved compared to the global motion analysis model. The computing resources required to run the CFD model are maintained below the practical limits for use during typical FPSO project engineering phase. CFD model simulation results for green water events of the FPSO platform are compared against available model test data and good agreement is observed. This paper demonstrates an application of CFD-based NWB for green water prediction for a spread-moored FPSO platform based on an optimized CFD model which is developed to enable fast simulation of green water events. To evaluate the susceptibility of a FPSO platform to green water, large numbers of green water event simulations will be required to obtain reliable statistical data.