scholarly journals Three-dimensional sloshing in a scaled membrane LNG tank under combined roll and pitch excitations

2020 ◽  
Vol 211 ◽  
pp. 107578 ◽  
Author(s):  
Min Luo ◽  
Xin Wang ◽  
Xin Jin ◽  
Bin Yan
Keyword(s):  
Three Dimensional ◽  
Lng Tank

Numerical Simulation of Two-Phase Sloshing Flow in LNG Tank Using Finite-Analytic Level-Set Method

2007 ◽  
Author(s):  
Kai Yu ◽  
Hamn-Ching Chen ◽  
Jang Whan Kim ◽  
Young-Bum Lee
Keyword(s):  
Numerical Simulation ◽  
Wave Breaking ◽  
Impact Load ◽  
Three Dimensional ◽  
Impact Pressure ◽  
Staggered Grid ◽  
Two Phase ◽  
Local Flow ◽  
Hull Structure ◽  
Lng Tank

Impact pressure due to sloshing is of great concern for the ship owners, designers and builders of the LNG carriers regarding the safety of LNG containment system and hull structure. Sloshing of LNG in a partially filled tank has been an active area of research with numerous experimental and numerical investigations over the past decade. In order to accurately predict the sloshing impact load, it is necessary to develop advanced numerical simulation tools which can provide accurate resolution of local flow phenomena including wave breaking, jet formation, gas entrapping and liquid-gas interactions. In the present study, a new numerical method is developed for the simulation of violent sloshing flow inside a three-dimensional LNG tank considering wave breaking and liquid-gas interaction. The sloshing flow inside a membrane-type LNG tank is simulated numerically using the Finite-Analytic Navier-Stokes (FANS) method. The governing equations for two-phase air and water flows are formulated in curvilinear coordinate system and discretized using the finite-analytic method on a non-staggered grid. Simulations were performed for LNG tank in transverse and longitudinal motions including horizontal, vertical, and rotational motions. The predicted impact pressures were compared with the corresponding experimental data. The validation results clearly illustrate the capability of the present two-phase FANS method for accurate prediction of impact pressure in sloshing LNG tank including violent free surface motion, three-dimensional instability and air trapping effects.

Numerical Study on Ship Motion Fully Coupled with LNG Tank Sloshing in CFD Method

2019 ◽  
Vol 16 (06) ◽  
pp. 1840022 ◽  
Author(s):  
Yuan Zhuang ◽  
Decheng Wan
Keyword(s):  
Incident Wave ◽  
Numerical Study ◽  
Three Dimensional ◽  
Ship Motion ◽  
Wave Flow ◽  
Motion Responses ◽  
Lng Tank ◽  
Cfd Method ◽  
Tank Sloshing ◽  
Fully Coupled

In this paper, numerical simulations of ship motion coupled with LNG tank sloshing in waves are considered. The fully coupled problems are performed by our in-house RANS/DES solver, naoe-FOAM-SJTU. The internal tank sloshing and external wave flow are solved simultaneously. The considered model is a three-dimensional simplified LNG FPSO with two prismatic tanks. The ship motion responses are carried out in beam waves to compare with existing experimental data to validate this solver. The coupling effects between ship motion and sloshing tanks are observed. The anti-rolling characteristics are found, and this kind of characteristic is obvious in low-filling conditions. Different incident wave amplitudes and frequencies are considered. When the incident wave frequency is close to ship motion natural frequency, the ship motion response is strong and an overturning behavior in sloshing tanks is observed. Meanwhile, impact pressures on bulkhead are also discussed. The pressure signal explains the phenomenon in tanks we discussed before.

Boil-Off Gas Formation inside Large Scale Liquefied Natural Gas (LNG) Tank Based on Specific Parameters

2012 ◽  
Vol 229-231 ◽  
pp. 690-694 ◽  
Author(s):  
Mohamad Shukri Zakaria ◽  
Kahar Osman ◽  
Md. Nor Musa
Keyword(s):  
Natural Gas ◽  
Large Scale ◽  
Seawater Temperature ◽  
Three Dimensional ◽  
Ambient Air ◽  
Calculation Model ◽  
Liquefied Natural Gas ◽  
Three Dimensional Model ◽  
Ambient Seawater ◽  
Lng Tank

Liquefied Natural Gas (LNG) fleets are coasting with various condition and behavior. These variable leads to different type of LNG fleets build every year with unavoidable generated Boil-off Gas (BOG). Estimation of BOG generated inside LNG tank play significant role in determines the ship specification and management method of BOG including venting, propulsion or requalification. Hence, in the present study, the right choices of boundary condition and parameter have been implementing in order to have good estimation amount of BOG evaporates for specific LNG tank. Three dimensional model of cargo with capacity 160000 m3 LNG carrier are simulate using ANSYS Fluent with specific ambient air temperature of 5oC and ambient seawater temperature of 0oC have been chosen as a calculation case, gain the total heat transfer rate and Boil-off Rate (BOR). The result shows that the calculation model and simulation are feasible with typical LNG fleet specification and International Marine Organization (IMO) standard.

3D SPH Numerical Investigation for the Sloshing Impact in LNG Tank

2013 ◽  
Author(s):  
Zhigang Bai ◽  
Jun Zhao ◽  
Wei Zhang ◽  
Weiling Wang
Keyword(s):  
Free Surface ◽  
Numerical Model ◽  
Numerical Technique ◽  
Three Dimensional ◽  
Liquid Sloshing ◽  
Dynamic Responses ◽  
Sph Method ◽  
Sph Model ◽  
Lng Tank ◽  
Liquid Natural Gas

Sloshing in liquid natural gas (LNG) tankers includes extremely large deformations of the free surface. To better understand such deformations, a three-dimensional Smoothed Particle Hydrodynamics (SPH) method is developed to analyze the dynamic responses of liquid sloshing in LNG tank. The numerical model solves the Euler equation in the SPH style, the Monaghan-type artificial viscosity has been used in the current SPH model, sloshing wall boundaries were treated by improved coupling boundary pressure treatment. The numerical model is first validated against experimental data for two-dimensional and three-dimensional liquid sloshing in a LNG tank, it shows a fair agreement of overall fluid motions and hydrodynamic pressures. The fields of 3D sloshing pressure and velocity are compared for one period. Finally, the model is used to study 3D liquid sloshing in a tank with vertical baffles. The effect of the baffle on pressure and velocity is investigated and discussed. It shows that the SPH method is a natural numerical technique for coupled fluid-structure problems with large free-surface deformations.

A Finite-Element Computation for Three-Dimensional Problems of Sloshing in LNG Tank

2006 ◽  
Author(s):  
J. W. Kim ◽  
I. H. Sim ◽  
J. M. Lee ◽  
Y. B. Lee ◽  
K. J. Bai
Keyword(s):  
Finite Element Method ◽  
Finite Element ◽  
Degrees Of Freedom ◽  
Three Dimensional ◽  
Impact Pressure ◽  
Numerical Result ◽  
Lng Tank ◽  
Three Dimensional Finite Element ◽  
The Impact ◽  
Element Method

A three-dimensional finite-element method is developed to calculate the impact pressure due to liquid sloshing in LNG tank. A finite-element method presented here is based on a variational principle in velocity-potential formulation, which was developed by Kim et al (ISOPE 2003). The tank motions are extended to the six degrees of freedom motions; both translational and rotational motions. Numerical result for an example of an LNG tank shows good agreement with model test results and three-dimensional effect needs to be considered to estimate correct impact pressure at tank corners.

Simulation of Sloshing in LNG-Tanks

2009 ◽  
Vol 131 (3) ◽  
Author(s):  
Milovan Peric ◽  
Tobias Zorn ◽  
Ould el Moctar ◽  
Thomas E. Schellin ◽  
Yong-Soo Kim
Keyword(s):  
Three Dimensional ◽  
Mesh Size ◽  
Breaking Waves ◽  
Ship Motions ◽  
Sea Waves ◽  
Interface Capturing ◽  
Grid Approach ◽  
Numerical Mixing ◽  
Lng Tank

The purpose of this paper was to demonstrate the application of a procedure to predict internal sloshing loads on partially filled tank walls of liquefied natural gas (LNG) tankers that are subject to the action of sea waves. The method is numerical. We used a moving grid approach and a finite-volume solution method designed to allow for arbitrary ship motions. An interface-capturing scheme that accounts for overturning and breaking waves computed the motion of liquid inside the tanks. The method suppressed numerical mixing. Mixing effects close to the interface were buried in the numerical treatment of the interface. This interface, which was at least one cell wide, amounted to about 20–50 cm at full scale. Droplets and bubbles smaller than mesh size were not resolved. Tank walls were considered rigid. The results are first presented for an LNG tank whose motion was prescribed in accordance with planned laboratory experiments. Both two-dimensional and three-dimensional simulations were performed. The aim was to demonstrate that (1) realistic loads can be predicted using grids of moderate fineness, (2) the numerical method accurately resolves the free surface even when severe fragmentation occurs, and (3) long-term simulations over many oscillation periods are possible without numerical mixing of liquid and gas. The coupled simulation of a sea-going full-sized LNG tanker with partially filled tanks demonstrated the plausibility of this approach. Comparative experimental data were unavailable for validation; however, results were plausible and encouraged further validation.

Three Dimensional Numerical Simulation of LNG Prestressed Tank

2012 ◽  
Vol 433-440 ◽  
pp. 1324-1332
Author(s):  
Xian He Du ◽  
Xin Pu Shen
Keyword(s):  
Numerical Simulation ◽  
Maximum Stress ◽  
Three Dimensional ◽  
Gas Pressure ◽  
Hydraulic Pressure ◽  
Live Load ◽  
Maximum Displacement ◽  
Tank Model ◽  
Temperature Method ◽  
Lng Tank

The purpose of this paper is to observe the distribution of displacement and stress of LNG prestressed tank when under the normal condition and the LNG divulging. The Abaqus software has been used to analyze the three dimensional LNG prestressed tank with finite element method, a numerical simulation is carried out by modeling the prestressed rebar with three dimensional elements, meanwhile, the prestress is applied for rebar with the falling temperature method. By coupling the condition of dead load, live load, prestress, gas pressure, hydraulic pressure and the low temperature, the conclusions indicate that: 1) the valid prestress has been applied by the prestressed rebar for LNG tank model. 2) the effect of live load for the tank can be ignored but the effect of gas pressure cannot. 3) the effect of highly temperature difference between the internal and external of LNG tank is great when the template lining of LNG tank divulging. The maximum displacement of cylinders shell is 28.22mm, and the maximum stress is 13.97MPa, the safety can be enhanced by modifying the arrangement of prestressed rebar.

The orbit of Pluto over a long interval of time

1966 ◽  
Vol 25 ◽  
pp. 227-229 ◽  
Author(s):  
D. Brouwer
Keyword(s):  
Periodic Orbit ◽  
Numerical Integration ◽  
Restricted Problem ◽  
Three Dimensional ◽  
The Third ◽  
Circular Restricted Problem ◽  
Resonance Relation

The paper presents a summary of the results obtained by C. J. Cohen and E. C. Hubbard, who established by numerical integration that a resonance relation exists between the orbits of Neptune and Pluto. The problem may be explored further by approximating the motion of Pluto by that of a particle with negligible mass in the three-dimensional (circular) restricted problem. The mass of Pluto and the eccentricity of Neptune's orbit are ignored in this approximation. Significant features of the problem appear to be the presence of two critical arguments and the possibility that the orbit may be related to a periodic orbit of the third kind.

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