The Effects of Sloshing on the Responses of an LNG Carrier Moored in a Side-by-side Configuration with an Offshore Plant

*American Bureau of Shipping, Houston, AmericaKEY WORDS: Sloshing 슬로싱, Global motion 거시적 운동, Coupled dynamic analysis 동적 연성 해석, Time domain potential-viscous hybrid method 시간영역 포텐셜-점성 혼합 방법ABSTRACT:During the loading/offloading operation of a liquefied natural gas carrier (LNGC) that is moored in a side-by-side configurati on with an offshore plant, sloshing that occurs due to the partially fille d LNG tank and the interactive effect between the two floating bodies are important factors that affect safety and operability. Therefore, a time-domain so ftware program, called CHARM3D, was developed to consider the i nteractions between sloshing and the motion of a floating body, as well as the inte ractions between multiple bodies using the potential-viscous hy brid method. For the simulation of a floating body in the time domain, hydrodynamic coefficients and wave forces were calculated in the frequency d omain using the 3D radiation/diffraction panel program based on potential theory. The calculated values were used for the simulation of a floatin g body in the time domain by convolution integrals. The liquid sloshing in the inner tank s is solved by the 3D-FDM Navier-Stokes solver that includes th e consideration of free-surface non-linearity through the SURF scheme. The compute d sloshing forces and moments were fed into the time integratio n of the ship’s motion, and the updated motion was, in turn, used as the excita tion force for liquid sloshing, which is repeated for the ensui ng time steps. For comparison, a sloshing motion coupled analysis program based on linear potential theory in the frequency domain was developed. The computer programs that were developed were applied to the side-by-side o ffloading operation between the offshore plant and the LNGC. The frequency-domain results reproduced the coupling effects qualitatively, but, in general, the peaks were over-predicted compared to experimental and time-domain results. The interactive effects between the sloshing liquid and the mot ion of the vessel can be intensified further in the case of mul tiple floating bodies.교신저자 이승재: 16855 Northchase Dr., Houston, 77060, sjlee@eagle.org본 연구는 2008년 제주도에서 개최된 International Workshop on Water Waves and Floating Bodies 에 발표된 논문을 근간으로 하고 있음을 밝힙니다.