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Study on sloshing simulation in the independent tank for an

ice-breaking LNG carrier

Shifeng Ding

a

, Gang Wang

b,*

, Qiuming Luo

b

aSchool of Naval Architecture and Ocean Engineering, Jiangsu University of Science and Technology, Zhenjiang, 212003, China bShanghai Rules and Research Institute, China Classification Society (CCS), Shanghai, 200135, China

a r t i c l e i n f o

Article history:

Received 29 September 2019 Received in revised form 19 February 2020 Accepted 3 March 2020

Keywords: Ice breaking force Liquid sloshing Couple analysis Independent LNG Carrier Discretized ice boundary method

a b s t r a c t

As the LNG carrier operates in ice covered waters, it is key to ensure the overall safety, which is related to the coupling effect of ice-breaking process and internal liquid sloshing. This paper focuses on the sloshing simulation of the ice-breaking LNG carrier, and the numerical method is proposed using Circumferential Crack Method (CCM) and Volume of Vluid (VOF) with two main key factors (velocity vx

and force Fx). The ship motion analysis is carried out by CCM when the ship navigates in the ice-covered

waters with a constant propulsion power. The velocity vxis gained, which is the initial excitation

con-dition for the calculation of internal sloshing force Fx. Then, the ship motion is modified based on iterative computations under the union action of ice-breaking force and liquid sloshing load. The sloshing simulation under the LNG tank is studied with the modified ship motion. Moreover, an ice-breaking LNG ship with three-leaf type tank is used for case study. The internal LNG sloshing is simulated with three different liquid heights, including free surface shape and sloshing pressure distribution at a given moment, pressure curves at monitoring points on the bulkhead. This present method is effective to solve the sloshing simulation during ice-breaking process, which could be a good reference for the design of the polar ice-breaking LNG carrier.

© 2020 Society of Naval Architects of Korea. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creativecommons.org/licenses/by-nc-nd/4.0/).

1. Introduction

Sloshing study develops rapidly in recent years for the appli-cation of liquefied natural gas (LNG) Floating Production Storage and Offloading (FPSO) (Ryu et al., 2016) and LNG carrier (Liu et al. (2015)) The main methods include model test and numerical simulation. Model test of sloshing is intuitive and effective, but it is also difficult and expensive.Jiang et al. (2018) carried out the sloshing test to study the hydroelastic effect of sloshing with different excitation frequencies. Zabihi et al., 2019 used a 1:15 scaledfixed offshore Oscillating Water Column (OWC) model to test the complicated hydrodynamic behavior. Sanapala et al. (2019) performed shake table experiments to study thefluid structure interaction effects between the sloshing liquid and the internal structure.Yu et al., 2019studied on the shallow water sloshing in a tank under horizontal excitation to investigate the reducing effect of vertical slat screens by the six degree of freedom motion simu-lation platform. However, there are some uncontrollable factors in

the model tests, which are related to the capability and accuracy of equipment.

Numerical method became popular and reliable with the development of computer technology.Hitoshi et al. (2014)studied two schemes for enhancement of incompressible smoothed parti-cle hydrodynamics(ISPH)-based methods in simulation of violent sloshingflows and sloshing induced impact pressures, including a higher order laplacian and an error-compensating source of pois-son pressure equation. Zhang et al., 2016proposed a meshless numerical scheme based on the generalized finite difference method, which was used to simulate the sloshing phenomenon in a two-dimensional numerical wave tank.Jena and Biswal, 2017 car-ried out a numerical study on violent liquid sloshing phenomenon in partially filled rectangular container by using Moving Particle Semi-implicit (MPS) method.Jin et al. (2017)studied on the reso-nant sloshing in a swaying tank with a submerged horizontal perforated plate by a numerical model based on the open source field operation and manipulation, which was validated by experi-mental data.Guan et al. (2018)developed the topology optimiza-tion and optimal control methods to design the shape of the board by Volume of Fluid (VOF) method.Green and Peiro, 2018proposed a * Corresponding author. [email protected]

Peer review under responsibility of Society of Naval Architects of Korea.

https://doi.org/10.1016/j.ijnaoe.2020.03.002

2092-6782/© 2020 Society of Naval Architects of Korea. Production and hosting by Elsevier B.V. This is an open access article under the CC BY-NC-ND license (http://creative commons.org/licenses/by-nc-nd/4.0/).

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SPH method to simulate the long duration sloshing with lowfill ratios, and the numerical result accurately matched the experi-mental data.Su et al. (2018)studied on the shallow-water sloshing in a two-dimensional rectangular tank based on the highly accurate Boussinesq-type equations considering small excitation of sway, heave and roll motions.Akkaoui et al. (2019)studied on the reso-nance of the free surface of water contained in a thin elastic cy-lindrical tank by an advanced nonlinearfluidestructure reduced-order computational model.Simoninia et al. (2019)presented an improved algorithm enhancing the accuracy of the velocity vector detection in dynamic wavy flows, which improved the spatial resolution on capturing the interface of liquid sloshing.Wang et al. (2019)worked on the sloshing simulation of liquid in the half-full horizontal circular cylindrical by the isogeometric scaled bound-aryfinite element method.Dai et al. (2019)studied on the dynamic response of a partiallyfilled freight train subject to abrupt braking using the moving element method.

These numerical researches disregard the couple effect between liquid and its container, which becomes a new topic for study. Khayyer et al., 2018presented thefirst semi-implicit/explicit ISPH-SPH coupled method for Fluid-Structure Interaction (FSI) related to deformable elastic structures with comprehensive validations and performance investigations.Huang et al., 2018developed a coupled nonlinear time-domain simulation scheme for nonlinear in-teractions among sloshingflows and floating body motion for both regular and irregular wave excitation. Saripilli and Sen, 2018 studied on the effect of coupling between sloshing and ship mo-tions in the evaluation of slosh-induced interior pressures, how-ever, the differences in the pressures between coupled and uncoupled cases may reach 100% or more.Sun et al. (2019)found many multiple peaks appeared in the coupled roll motion by comparing the motion responses of the ship with different tank filling levels. Rawat et al., 2019evaluated the sloshing ment, base shear, hydrodynamic pressure, and bearing displace-ment responses in a three-dimensional (3-D) rigid and flexible tanks subjected to bi-directional components of earthquake ground motions.

Medium and small independent LNG carriers provide an effec-tive way for transporting LNG resources in the icy waters. As the LNG carrier navigates in ice-covered waters, the ship's velocity is slightly oscillating under the dynamic icebreaking force (Wang, 2001;Hu and Zhou, 2015,2016;Zhou et al., 2013,2017,Zhou et al., 2019, Zhou et al., 2020). It is an interesting to analyze the coupling between the ice-breaking and liquid sloshing.Seo et al., 2017studied on the motion responses and added resistance of a ship, coupled with the sloshing-induced internal forces and mo-ments which were considered by using the linear potential theory. The result showed that the sloshing inside the tanks may signi fi-cantly influence not only the motion responses, but also added resistance. That phenomenon also appears in the LNG carrier navigating in the ice-covered waters. The ice-breaking motion is an excitation factor for liquid sloshing in the tank, while the internal sloshing-induced forces affects the ice-breaking motion at the same time. Some anti-sloshing measures were proposed to reduce the sloshing load of the independent LNG carrier (Zhang et al. (2017), Liu et al., 2015).

This paper aims at developing a numerical simulation method for liquid sloshing in the independent LNG tank during the ice-breaking process. Two key factors (velocity vx and force Fx) are

selected to consider the coupled action between ice-breaking and liquid sloshing. The Circumferential Crack Method (CCM) is used to simulate the ice-force and ship velocity disregarding the effect of liquid motion at initial stage.

2. Numerical method study

2.1. Mechanical interaction model of ship and ice

The CCM is an effective method to simulate the interaction of ship and ice (Zhou et al., 2017)). The iceehull interaction is simu-lated by a basic geometric model consisting of the ship's full-scale waterline and the ice's edge. In the established simulation pro-gram, a closed polygon is used to describe the ship's waterline and a polyline is used to describe the ice's edge. The simulation program is carried out to detect the boundary between the ship hull and the ice boundary at each time interval. The contact surface is assumed to beflat and the contact area is determined by the length and the depth of the indentation.

The interaction between ship hull and sea ice is the key to simulate the ice-breaking process, which is derived fromEq. (1).

R¼ Cl$l  1:0 þ CV$ vreln  (1) where,vrel

n is the relative normal velocity between the ice and the

hull node, Clis an empirical parameter with a positive value, while CVis an empirical parameter with a negative value, l is taken asEq.

(2), which is the length of level ice.

l¼ Eih3i 121

y

2

r

wg !1=4

(2)

where, Eiis level ice's elasticity modulus, hiis the ice thickness,

y

is

ice's poisson ratio,

r

w is water's density, g is gravitational

acceleration.

The crushing force Fi is normal to the contact surface and taken asEq. (3). This force is the important component of ice load, which is related to the ice's effective crushing strength and the contact area between ship and ice.

Fi¼ Cf 

q

p

2

s

fh2i (3)

where,

q

is the angle of the idealized ice circular crack,

s

f is the

flexural strength, and Cfis an empirical parameter to modify the ice

crushing force.

The CCM method on ice-breaking analysis has been verified well by ice basin test.Zhou et al. (2013,2018)carried out model tests (as shown inFig. 2) on an ice-breaking ship in the ice basin of the Marine Technology Group in the Aalto University, and compared the results between numerical method and model test asFig. 3.

The comparison results show the good consistency between the CCM and the test method. The maximum difference compared to model test is about 6.38%, which is much lower than that of empirical formula results. Therefore, the CCM is chosen for the further study in this paper.

As the propulsion power is a constant value,Eq. (4)is set up to calculate the relationship between ship velocity and ice force.

P¼ Fi$vx (4)

where,vxis the ship velocity as shown inFig. 1, P is the propulsion

power.

The interaction between sea ice and ship hull is a discontinuous process, therefore, the velocityvxis a time-domain value. It is the

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2.2. Hydrodynamic model of liquid tank

LNG is a typical incompressible inviscidfluid, and Reynolds-Averaged Navier-Stokes(RANS) equations is suit for simulating the liquid sloshing with VOF method, which is widely applied in the field of computational fluid dynamics.

A volume function asEq. (5)is introduced to track the free liquid surface. Continuity equation:V $ ð

l

.uÞ ¼ 0 Momentum equation: v u . vt¼  1

r

Vp þ F!bþ

m

r

V2u . (5)

Volume fraction transfer equation: Dð

l

FÞ Dt ¼ 0

where, t is time, F is volume offluid, 1 for liquid, 0 for air, u.isfluid velocity vector,

r

is density of liquid, taken 0.45 t/m3for LNG, p is pressure of liquid, F!b is the external force including gravity and inertial forces,

m

is dynamic-viscosity coefficient.

The entail computing domain is divided into rigid mesh and fluid mesh, andEq. (5)is discretized by two-step projection method as follow, unþ1iþ1=2;j¼ un iþ1=2;j þ

D

t " Fby;iþ1=2;jn   uvu vyþ v vu vz n iþ1=2;jþ v v2u vy2þ v2u vz2 !n iþ1=2;j # vnþ1 iþ1=2;j¼ vniþ1=2;j þ

D

t " Fbz;iþ1=2;jn   uvv vyþ v vv vz n iþ1=2;jþ v v2v vy2þ v2v vz2 !n iþ1=2;j # pnþ1iþ1;jpnþ1 i;j

D

x2

l

r pnþ1i;j pnþ1 i1;j

D

x2

l

l ! þ p nþ1 iþ1;jpnþ1i;j

D

y2

l

t pnþ1i;j pnþ1 i1;j

D

y2

l

b ! ¼

D

r

tnþ1 ~unþ1

iþ1=2;j~unþ1i1=2;j

D

x þ ~vnþ1 iþ1=2;j~vnþ1i1=2;j

D

y ! (6) Fnþ1ði; jÞ ¼ Fnði; jÞ   Ft

l

tþ Fr

l

rþ Fl

l

l

l



The k ε turbulence equation and dynamic mesh technique is used for the hydrodynamic analysis, the followEq. (7)andEq. (8) should be satisfied at the boundary conditions. AndEq. (9) and Fig. 1. Interaction of ship and ice (Hu and Zhou, 2015).

Fig. 2. Model test design in ice basin (Zhou et al., 2018).

Fig. 3. Ice load comparisons among the CCM, model test measurement and the empirical formula.

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Eq. (10)should be satisfied at the boundary of tank. vvn vt þ vvc vn¼ 0 (7) pLþ 2

m

vvvnn¼  pA

r

(8) u . $ e.t¼ u.b$ e . t (9) u . $ e.n¼ u.b$ e . n (10)

where, unand utare the velocity in normal and tangential of liquid

free surface, pLand pAare pressure offluid and air. e.tand e.nare

the tangential and normal unit vectors, u.bis the velocity of tank in

the ship's coordinate system, taken as 0 considering the rigid boundary.

The overall sloshing force Fxis obtained for the whole tank with

Eq. (11).

Fx¼ ∬ BHD

pLdydz (11)

Ge et al. (2018)carried out the sloshing test in National Engi-neering Research Center of Shipbuilding, Dalian University of Technology. The result showed that the VOF method was in good consistence with the test results. There were also some similar conclusions in previous papers by other researchers (Jin et al.(2017),Guan et al. (2018)), thus, the VOF method is chosen in this paper.

The mesh sensitivity study is carried out considering three different mesh sizes for the three-leaf tank model (Fig. 4). The common office computer with i5 7500 CPU is used for this calcu-lation, and the major factors are listed inTable 1.

The tank model is assumed to be static at initial phase. It is partly filled with LNG, the loading height is 6m. The model is speeded up to 3 m/s with a constant accelerated velocity 0.1 m/s2. The simulation duration of the entire sloshing process is 30s. The sloshing phenomenon at 18s with 0.35 mesh size is shown inFig. 5, including wave shape and sloshing pressure distribution, which is similar for other mesh sizes.

From Fig. 5, the sloshing phenomenon is non-violent in the

assumed excitation condition. Furtherly, two monitoring points (0, 0, 6) and (0, 3, 6) are selected to compare the difference between different mesh sizes. The results are shown inFig. 6.

With the decrease of grid size, the pressure results show a tendency of convergence, but increase rapidly in computing time. Therefore, the mesh size is determined to 0.35m for the three-leaf tank model, which is a balance between computational accuracy and time for non-violent sloshing simulation.

2.3. Analysis on sloshing with ice-breaking load

As the LNG carrier navigates in ice waters with partial loading, the liquid sloshing load and ice-breaking load exist simultaneously and impact each other. In order to gain the modified velocity curves under the combined action of sloshing and ice-breaking,Eq. (3) and (8)are taken intoEq. (4), then,

v0x¼ P

ðFiþ FsÞ (12)

where,v0

xis the modified velocity for LNG carrier.

The detailed implementation process is presented as Fig. 7.Where,vxandv0xis the average ship velocity.

FromFig. 7, the ship motion analysis is carried out to gain the ship velocity vxduring ice-breaking without the effect of liquid

cargo atfirst. The sloshing induced force Fxare calculated. And the

ship velocity v'x is modified based on iterative computations

considering the union action of ice-breaking force and internal sloshing force, which is the final excitation condition for liquid sloshing simulation.

3. Case study

3.1. The main parameters of LNG carrier

An ice-breaking independent LNG carrier is used for case study, the main parameters of tank are listed inTable 2. The ideal level ice condition is assumed by this paper, whose physical characteristics are listed inTable 3.

3.2. Ice-breaking motion without liquid effect

At the initial moment, the ship is static in the ice waters, and it speeds up with the constant propulsion power. The ice resistance (Fx) of LNG carrier during ice breaking process is shown inFig. 8.

The ice force is changed periodically by time, whose minimal value is about 1650 kN and maximum value is about 3100 kN. The time domain velocity curves without the effect of liquid are calculated as Fig. 9.

FromFig. 9, the velocity curve can be divided into two parts obviously. Firstly, the ship speeds up quickly from static state to motion state, the acceleration magnitude can reach 0.13 m/s2. Secondly, the ship velocityfluctuates around a constant value, the period is about 0.9s and the amplitude is about 0.025 m/s. Fig. 4. The location and dimension of LNG tank.

Table 1

The calculation cases for mesh sensitivity study.

Case No. Mesh size Node number Element number Computing time

1 0.5m 362291 257413 0.8h

2 0.35m 826195 591490 2.3h

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3.3. Sloshing force excited by ice-breaking

The three-leaf tank is the novel cargo containment system in-dependent for medium inin-dependent LNG carrier as shown inFig. 4, whose dimension is listed inTable 2. Considering the cargo tank is partially loaded, three typical liquid heights are set to be 1/3h, 1/2h, and 2/3h respectively (h is height of cargo tank). The velocity curve shown inFig. 9is used as the excitation condition for the liquid sloshing of the ice-breaking LNG carrier. The sloshing reaction force Fxof internal sloshing is calculated based on VOF method byfluent

software. The results are shown inFig. 10.

From Fig. 10, the sloshing reaction force Fxoscillates and

at-tenuates with time referring to liquid heights. The force curves attenuate rapidly with low liquid height and vice versa. The sloshing load gradually enters a relatively stable state by the time. From the amplified load curves from 175s to 200s (the right figures inFig. 9), the sloshing reaction force is around 110 kN with 1/3h

liquid height, 155 kN with 1/2h liquid height and 250 kN with 2/3h liquid height. It indicates that the higher the liquid load is, the larger the sloshing reaction force on whole ship is.

The sloshing reaction force curves also appear obvious period-ical tendency, including the large reciprocating period and small oscillating period. The reciprocating period is about 8se15s due to the different liquid heights, and the oscillating period is about 0.8s. The large reciprocating period is the significant features for the sloshing reaction force curves with low loading height, while the oscillating period is the dominant pattern of sloshing reaction load curves.

3.4. Ship motion due to the ice-breaking and sloshing

The ship velocity curves are simulated under the combined ac-tion of liquid sloshing and ice-breaking. The simulaac-tion results are shown inFig. 11.

Fig. 5. Sloshing simulation of three-leaf tank model with 0.35m mesh size (at 18s).

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FromFig. 10, the time-domain velocity curves could be divided into three phases obviously. Thefirst phase, namely “speed-up”, lasts about 18s. The velocity curves increase rapidly from static Fig. 7. Flowchart of the proposed couple analysis on sloshing excited by ice-breaking.

Table 2 Dimension of LNG tank. Parameter Value Length l/m 32.0 Breadth b/m 18.0 Height h/m 18.0

Spacing of each tank s/m 6.0 Loaded height hLNG/m 6/9/12

Table 3

Physical characteristics of sea ice.

Parameter Value

Ice thickness hi/m 0.5

Flexural strengthsb/kPa 914

Crush strengthsc/kPa 2075

Elasticity modulus Ei/mPa 914

Velocityv/(m/s) 0.5

Heading anglej/() 90

Density of sea waterrw/kgm3 988.9

Density of iceri/kgm3 905.8

Friction coefficientmi 0.04

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state. The liquid sloshing slows down the acceleration process, and it is more obvious under the higher liquid height. The velocity curves show inflexion at this phase. Clearly, v1/3h, v1/2hand v2/3hare

the inflexion points for the velocity curves referred to different liquid heights. The second phase, namely“sloshing developing”, lasts about 120s. The liquid motion develops rapidly and fully, and Fig. 9. Velocity of LNG carrier during ice breaking disregard of liquid effect.

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the periodic tendency appears in the velocity curves. The period is around 11s. The last phase, namely “stable coupling”, the ice-breaking action interacts with liquid sloshing action to form a steady coupling state. The lower the loading height, the greater the effect on the velocity curves.

3.5. Simulation of liquid sloshing with different loading heights The liquid sloshing is simulated with different loading heights as shown inFigs. 12e14. The results presents the shape of liquid free surface (leftfigures) and distribution of pressure (right figures).

The liquid free surface appears slightly fluctuating tendency with 1/3h loading height. The major sloshing characteristics are small breaking waves. The principal direction of sloshing is along the ship length, which relates to the excitation condition of vx. The

sloshing pressure is a little larger than the static state pressure

without sloshing action. The increasing rate is about 3% at 54s, increasing from 26.4 kPa to 27.2 kPa.

The liquid free surface appears slightlyfluctuating with 1/2h loading height. The amplitude of sloshing wave is about 0.5 m at 53s. The sloshing pressure is slightly larger than the static pressure without sloshing action. The increasing rate is about 1.3%, increasing from 39.7 kPa to 40.2 kPa.

The liquid free surface appears slightlyfluctuating with 2/3h loading height. The shape of liquid free surface changes regularly and linearly. The sloshing pressure is slightly larger than the static pressure without sloshing action. The increasing rate is about 0.95%, increasing from 52.9 kPa to 53.4 kPa.

From above, the liquid sloshing excited by ship velocity curves of ice-breaking LNG carrier is slight. The major sloshing characteris-tics are small breaking waves. The increase rate of sloshing pressure compared to the static pressure is small, under 3%.

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3.6. Sloshing pressure near the liquid surface

Although the whole sloshing phenomenon is non-violent, the pressure fluctuation near the free surface is necessary to be

investigated further. Two points are set to be monitored at the end side of LNG tank, one point is at the position of (0, 0, h) and the other is at the position of (0, 3, h). Taking numerical sloshing model of 1/3h height as an example, the monitoring points are Fig. 12. Sloshing simulation with 1/3h loading height(at 54s).

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shown inFig. 15.

The time-domain monitoring pressure curves near the liquid surface are shown inFigs. 16e18with different liquid heights. The leftfigures are the pressure curves of whole process (0se300s) and the rightfigures are the pressure local amplified curves under the stable sloshing stage (150se175s). The three phases are also marked at the time-domain pressure curves according to the excitation condition shown inFig. 16.

With the low liquid height (1/3h), the sloshing pressure in-creases sharply at “speed up” phase, the maximum transient pressure reaches 310Pa. It attenuates rapidly latter at the“sloshing developing” phase, the transient maximum pressure decreases to 80Pa. Eventually, the sloshing pressure curve gradually attenuates by the time at the“stable coupling” phase, the range of dynamically amplitude is about 25e40 Pa. In addition, the sloshing pressure

curves of P1 and P2 are similar in shape while their amplitude

values are slightly different due to the location of monitoring points.

With the medium liquid height (1/2h), the maximum transient pressure reaches up to 210 Pa at“speed up” phase which is much lower than that of 1/3h liquid height, and the range of dynamically amplitude is about 15 Pa at the“stable coupling” phase. It indicates that the intensity of liquid sloshing is decreasing with the increasing of liquid height from 1/3h to 1/2h.

With the high liquid height (2/3h), the transient maximum pressure reaches 170 Pa at“speed up” phase which is the lowest among the sloshing simulations of three liquid heights. The range of dynamically amplitude is about 10 Pa at the“stable coupling” phase. The time-domain pressure curves are slightly different from lower liquid heights, including the speed of sloshing attenuating and obvious frequency of oscillation.

According to the above results, the main dynamic tendency is regularly reciprocating characteristic and rapidly oscillating char-acteristic for the ice-breaking LNG carrier. It will affect the local fatigue strength at the hotspot of structure (Zhang et al., 2017). Hence, the sloshing load needs to be considered fully for the structural design of the cargo containments of independent ice-breaking LNG carrier.

4. Conclusion

Both the ice load force and internal sloshing force affect the safety of the polar LNG carrier. Thus, it is practical to study the numerical simulation of sloshing in LNG tank during the ice-breaking process. This paper develops a method to consider the union action between ice-breaking and liquid sloshing, and some meaningful conclusions are presented as follow.

(1) The internal sloshing force Fximpacts ship's motion

perfor-mance, which slows down the ship velocity during the “speed up” phase, and enlarges the amplitude at the later Fig. 14. Sloshing simulation with 2/3h loading height (at 54s).

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Fig. 16. Monitoring pressure with 1/3h loading height.

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phases. It becomes obvious with the increase of loading level, which is a disadvantage on the ice-breaking capability of the polar ship.

(2) The sloshing phenomenon is non-violent during the ice-breaking process, and Fa the liquid free surfacefluctuates slightly under the excitation. Nevertheless, the dynamic pressure is obvious near the liquid surface, and it decreases with the increase of loading height.

(3) The sloshing period in the LNG tank is about 8se12s due to different liquid heights, which may overlap with the ship motion period during ice-breaking process. It is the key to design the ice-breaking capability for the polar ship.

Acknowledgements

This research was funded by the State Key Laboratory of Ocean Engineering (Shanghai Jiao Tong University), grant number 1807. References

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Saripilli, J.R., Sen, D., 2018. Sloshing-coupled ship motion algorithm for estimation of slosh-induced pressures. J. Mar. Sci. Appl. 17, 312e329.

Seo, M.G., Kim, Y., Park, D.M., 2017. Effect of internal sloshing on added resistance of ship. J. Hydrodyn. 29 (1), 13e26.

Simoninia, A., Theunissen, R., Masullo, A., Vetrano, M.R., 2019. PIV adaptive inter-rogation and sampling with image projection applied to water sloshing. Exp. Therm. Fluid Sci. 102, 559e574.

Su, Y., Liu, Z.Y., Gao, Z.L., 2018. Shallow-water sloshing motions in rectangular tank in general motions based on Boussinesq-type equations. J. Hydrodyn. 30 (5), 958e961.

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Zabihi, M., Mazaheri, S., Namin, M.M., 2019. Experimental hydrodynamic investi-gation of afixed offshore Oscillating Water Column device. Appl. Ocean Res. 85, 20e33.

Zhang, J.P., Shao, Z.F., Yang, Y., Xie, Y.H., 2017. Research on motion response and structure response of oil tanker thinking about liquid sloshing. Ship Build. China 58 (4), 83e90.

breaking capability for a double acting polar ship. J. Mar. Sci. Eng. 8 (179)

https://doi.org/10.3390/jmse8030179.

Zhang, T., Yu, F.R., Fan, C.M., Li, P.W., 2016. Simulation of two-dimensional sloshing phenomenon by generalizedfinite difference method. Eng. Anal. Bound. Elem. 63, 82e91.

수치

Fig. 2. Model test design in ice basin ( Zhou et al., 2018 ).
Fig. 5. Sloshing simulation of three-leaf tank model with 0.35m mesh size (at 18s).
Table 2 Dimension of LNG tank. Parameter Value Length l/m 32.0 Breadth b/m 18.0 Height h/m 18.0
Fig. 10. The force curves of internal sloshing on whole ship.
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