RANS prediction of FLNG-LNG hydrodynamic interactions in steady current

Abstract

The hydrodynamic interaction between a floating liquefied natural gas system (FLNG) and a liquefied natural gas carrier (LNG) has been studied in steady current using a Reynolds Averaged Navier-Stokes solver. A double body approximation method is adopted to investigate the hydrodynamics of the two vessels in close proximity neglecting the free surface effects. Initially, five benchmark ship–ship interaction cases combining different flow speeds, drafts and relative positions are replicated. Comparisons with measured test data and with computational results from literature are made, suggesting the flow field, pressure distribution and forces and moments acting on the hulls are well predicted. Using the validated numerical setup, systematic computations on the hydrodynamic interactions of the FLNG-LNG offloading system have been carried out in steady current. The forces and moments on the hulls with varying relative longitudinal and lateral separations are estimated and explained. Furthermore, full scale computations are conducted to quantify scale effects existing in the present study. From the obtained results, scale effects are evident in the surge force but found to be much less influential in the sway force, roll moment and yaw moment predictions for the cases tested.