Numerical study of free surface flow in a 3-dimensional FLNG tank under coupled rotational–heave excitations
In this paper, free surface flow in a full-sized 3D FLNG tank is numerically studied under coupled rotational–heave excitations. The numerical model uses the standard k–ε turbulence model and the volume of fluid method to describe fluid flow and track free surface. The emphasis of this study is making use of a full-sized tank with coupled excitations. A mesh independence study and comparison with other experiment and numerical simulation are implemented to verify the computational model. By parametrically investigating the influence of the initial phase difference, heave frequency and filling ratio, it is found that an initial phase difference of 0.5π and 1π can result in a higher local pressure near the tank corner and 0.5π will lead to a bigger amplitude of surface sloshing. A heave frequency of 2 times the natural frequency makes the surface sloshing flow most violent, but a heave frequency larger than that will turn the sloshing pattern into an up-and-down oscillation. A low filling ratio is more sensitive to both single rotational excitation and coupled excitations. However, a high filling ratio is relatively stable under rotation alone, but becomes much more violent from an induced heave excitation.
KeywordsCoupling excitations Volume of fluid method Free surface flow FLNG tank
This research is sponsored by prospective Project (BY2014127-06) and cooperation with Furui SE Co., Ltd (BK2013092); both are supported by Science and Technology Department of Jiangsu Province, China and also by the Fundamental Research Funds for the Central Universities and Scientific Research Innovation Project for Graduate Students in Jiangsu Province (KYLX15_0060).
- 1.Union IG (2015) World LNG Report—2015 editionGoogle Scholar
- 2.Colella P, Graves DT, Modiano D, Puckett EG, Sussman M (1999) An embedded boundary/volume of fluid method for free surface flows in irregular geometries. 3rd ASME/JSME joint fluids engineering conference ASME Paper FEDSM99-7108, pp 9–14Google Scholar
- 9.Zalar M, Malenica S, Mravak Z, Moirod N (2007) Some aspects of direct calculation methods for the assessment of LNG tank structure under sloshing impact. In: Proceedings of the international conference on liquefied natural gas, Barcelona, Spain, PO-39.1Google Scholar
- 11.Newman JN (2005) Wave effects on vessels with internal tanks. 20th Workshop on water waves and floating bodies, SpitsbergenGoogle Scholar
- 12.Kim Y (2002) A numerical study on sloshing flows coupled with ship motion—the anti-rolling tank problem. J Ship Res 46:52–62Google Scholar