The Numerical Simulation of LNG Sloshing With an Improved Volume of Fluid Method

Abstract

With the trend towards offshore LNG production and offloading, sloshing of LNG in partially filled tanks has become an important research subject for the offshore industry. LNG sloshing can induce impact pressures on the containment system and can affect the motions of the LNG carrier. So far, LNG sloshing was mainly studied using model tests with an oscillation tank. However, the development of Navier-Stokes solvers with a detailed handling of the free surface, nowadays allows the numerical simulation of sloshing. It should be investigated, however, how accurate the results of this type of simulations are for this complex flow problem. The present paper first presents the details of a numerical model, an improved Volume OF Fluid (iVOF) method. Comparisons are made with sloshing model test results. Based on the results, the following conclusions can be drawn: - The dynamics of sloshing in LNG tanks can be simulated numerically using an iVOF Navier-Stokes solver. - Several improvements have been made in the treatment of numerical spikes in the pressure signals, but still more improvements need to be made. - Qualitatively, the pressure pulses resulting from impacts against the LNG tank wall show a rather good agreement between experiment and numerical simulation. - Quantitatively, the differences with the experiment show that further detailed studies with respect to cell sizes and time steps are necessary.

Toward a Probabilistic Approach to Determine Nominal Values of Tank Sloshing Loads in Structural Design of Liquefied Natural Gas FPSOs

“…(5) Before the sloshing characteristics should be used to study the structural response, it is highly recommended that sound statistical evaluation of impact characteristics should be is investigated. (6) The sloshing probability calculated in this study is based on a limited amount of numerical motion data. It is, thus, expected that field measured data or increased number of motion data would improve the accuracy of the sloshing probability.…”

Modeling Two-Phase Flow With Offshore Applications

“…The results of the calculations are compared with experimentally obtained loads and with the results of a one-phase numerical model [7].…”

Numerical simulation of 3D sloshing flow in partially filled LNG tank using a coupled level-set and volume-of-fluid method

“…Kim (2001Kim ( , 2004 used the SOLA-SURF program to simulate the sloshing problem in rectangular and prismatic tanks. Loots et al (2004) presented an improved Volume of Fluid (iVOF) method to numerically produce the dynamics of sloshing in LNG tanks, with several improvements in the treatment of spikes for the pressure signals. Wemmenhove et al (2005) extended iVOF method to incorporate two-phase flow and improved the method to simulate the effect of gas bubbles of different sizes.…”