Motion responses of a liquefied natural gas-floating production storage and offloading unit coupled with sloshing excitation

Abstract

This paper considers the motion responses of an LNG-FPSO in regular waves. Particularly, the LNG-FPSO has two partially filled tanks, so that the sloshing-induced force and moment affect the floating body motion. The method of solution is a three-dimensional Rankine panel method that represents the physical quantities by using a B-spline basis function. The sloshing flows in the two tanks are also simulated by using the Rankine panel method. All the boundary value problems are linearised, and the solutions are compared with the experimental data measured at a towing tank. Although the overall trends are similar, a difference of frequency of peak roll response amplitude operator (RAOs) is observed between the linear solution and experiment. The LNG-FPSO model considered in this study has a resonance between the roll motion and sloshing in a very low filling condition; therefore, the coupling effect is not strong.