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This paper presents a Fluid-Structure Interaction (FSI) numerical study of a deformable two-dimensional floating rectangular tank partially filled with water and subjected to a regular wave effect. It is based on the coupling of a two-phase flow solver from the OpenFOAM code, based on the Finite Volume Method (FVM), and an elastic solid solver from the FEniCS code, based on the Finite Element Method (FEM). The two solvers are coupled using the preCICE library for the Fluid-Structure Interaction (FSI) problem. The Arbitrary Lagrangian-Eulerian (ALE) formulation is adopted for the two-phase Navier-Stokes equations in a moving fluid domain. An implicit coupling scheme is used to solve the FSI problem. The effect of swell excitation is considered by introducing a source term into the equations governing the fluid and the solid. The obtained results show that for the studied case, the tank walls' flexibility increases the sloshing amplitude and the fluctuations at the air-liquid interface, and causes a phase shift in the free surface response compared to the rigid case. The Fast Fourier Transform (FFT) applied to the time responses of the free surface and the tank wall highlights that the obtained results give a good agreement with the analytical solution. [ABSTRACT FROM AUTHOR]

This paper aims to investigate the effect of liquid heterogeneity on sloshing in a two-dimensional rectangular tank. The container is excited horizontally, and the density of the liquid at equilibrium can almost be considered a linear dependence of the depth. The linearized equations representing the sloshing phenomenon are solved numerically using ANSYS 2020 R2 software and analytically using the separation method of variables in conjunction with the Fourier analysis. On the other hand, a comparison study has been carried out between the obtained results and other works related to the same phenomenon. Overall, the results exhibit considerable effects of variation in the Heterogeneity Coefficient β on the free surface's motion and the pressure distribution within the liquid. Furthermore, the free surface of liquid heterogeneity is also affected by the variation of Excitation Frequency Ω and the Filling Rate h of the liquid in the tank. [ABSTRACT FROM AUTHOR]

The main purpose of the current study is to design a control system for a sloshing system to suppress the vibration of functionally graded graphene platelet-reinforced composite (FG GPL-RC) on the top surface. A set of piezoelectric sensors and actuators are used for active control of fluid-structure coupling in transient seismic analysis of an inviscid liquid sloshing in a cylindrical tank. First, the top surface FG GPL-RC is optimized to satisfy maximum deformation, face failure, mid shear, and face wrinkling by changing the geometrical parameters and weight fraction distribution through the thickness. The nonlinear governing equations of nanocomposite panels with mechanical properties derived from the Halpin–Tsai model are solved by smoothed particle hydrodynamics (SPH) method. A parameter study counting the boundary condition effects, thickness-to-radius ratio, material distribution of the laminates, and dimensions of the sloshing tank on the FG GPL-RC natural frequencies are surveyed and explained in detail. Then, the frequency analysis of the plate with and without sloshing is performed while the inviscid fluid motion is modeled by SPH. The proposed method is validated with available data in the literature. Finally, the active control of the coupled system in response to the external disturbances is completed by a tuned proportional–integral–derivative (PID) controller which used the piezoelectric sheets on the top surface plate. The performance of the proposed control system is illustrated by a comparison of the controlled and uncontrolled transient responses of the coupled hydro-elastic system to the El-Centro seismic load. [ABSTRACT FROM AUTHOR]

This study investigates the effects of sway and roll excitations on sloshing liquid loads in a tank, using Ansys Fluent software. The model considered in the study is a 1:50 scaled membrane-type tank, based on a KC-1 membrane LNG tank designed by Korea Gas Corporation (KOGAS). The volume of fluid (VOF) method is used to track the free surface inside the tank, and the standard k-ε model is applied to express the turbulent flow of the liquid. To explore the motion of the tank under excitation, a user-defined function (UDF) and a dynamic mesh technique are employed to control the external forces exerted on the tank through its motion. The results, in the form of time series data on the sloshing pressures in the tank under pure sway, roll, and coupled sway-roll, are analysed, with specific ranges for the excitation amplitudes and frequencies. We show that variations in excitation frequency and amplitude significantly influence the sloshing loads. Sloshing loads are found to intensify when the excitation frequency matches the tank's primary natural frequency, 1.0 ω1′. Furthermore, with coupled sway-roll excitations, the sloshing loads are weakened when the sway and roll are in-phase and are intensified when these are out-of-phase. Fast Fourier transform analysis provides insights into the frequency domain, showing that the dominant frequency is 0.88 Hz and it is approximately equal to the tank's primary natural frequency, 1.0 ω1′. [ABSTRACT FROM AUTHOR]

Liquid sloshing, which occurs in all accelerating and liquid-carrying vehicles, is of great importance, especially in the automotive and aerospace industries. Large-scale fluid sloshing causes both operational and safety problems in vehicles. In this study, the fuel tank of a heavy vehicle with an emergency braking system is designed in three dimensions, and liquid sloshing in the fuel tank is investigated by CFD analysis method. VOF solution method, k-ε turbulence model, and PISO solution algorithm are used in the study. In the analysis of liquid sloshing, it is assumed that the vehicle is traveling at a certain speed, decelerates and stops with emergency braking, and remains stationary for a while. The braking scenario and boundary conditions are based on test data from a heavy vehicle manufacturer. The designed fuel tank with a capacity of 207.6 liters was analyzed at 25%, 50%, and 60% diesel fuel filling levels in 6 different cases with and without anti-slosh baffles. Four virtual sensors were placed on the side wall of the fuel tank in the direction of vehicle movement, and time-dependent pressure changes were analyzed for all cases. In addition, the fuel volume ratio in all cases is visualized and presented for specific time steps. With the use of anti-slosh baffles, the maximum pressure, the rate of pressure increase, and the liquid sloshing were reduced by a factor of 2-3 for different cases. With the design of the fuel tank using anti-slosh baffles, instantaneous interruptions in the fuel system are prevented. Reducing the impact pressures on the tank walls is expected to positively affect noise, vibration, and stability problems. [ABSTRACT FROM AUTHOR]

Major problems can occur when liquid sloshes in a tank, such as in liquid storage tanks during an earthquake, and this is an important engineering problem to address. To analyze this phenomenon, the finite-element method is generally used but involves many degrees of freedom when the tank is large. In this paper, a nonlinear numerical model with relatively few degrees of freedom is established for vertical and horizontal two-dimensional nonlinear sloshing in a rectangular tank excited horizontally. In addition, a method is proposed for reducing the number of degrees of freedom in the two-dimensional model. The natural frequencies, modes, and frequency responses are then compared among the concentrated mass model, theoretical calculations, and experimental results. Good agreement was achieved among them, thus demonstrating the validity of the model. [ABSTRACT FROM AUTHOR]

When a tank containing a liquid is excited externally, the free surface of the liquid becomes violently distorted, generating a large amount of wave energy. We suggest a novel model for harvesting wave energy produced by such sloshing. A deformable energy harvester with an attached piezoelectric patch is mounted vertically in the middle of a liquid tank. By varying the excitation amplitude and frequency of the tank, the level of water, and the thickness of the harvester, the dynamics of the harvester are investigated in terms of tip deflection and phase difference. The excitation frequency corresponding to sloshing resonance is critical for producing large tip deflections. Near resonance, the motions of the tank and the harvester are not necessarily synchronized, and there are large variations in the phase difference. The performance of the energy harvester is evaluated by measuring the open-circuit voltage, short-circuit current, and output power with an electrical load. The model has exceptional power generation performance and would be suitable for supplying power to small electrical devices. Moreover, the harvester is effective in suppressing the peak hydrodynamic pressure exerted on the tank wall, which suggests dual functions of our model as an energy harvester and as a baffle. [Display omitted] • A bendable piezoelectric patch harvests energy from sloshing in a liquid tank. • Optimal conditions for energy harvesting are identified based on tip deflection. • Phase difference between tank and harvester varies notably near slosh resonance. • Slosh-induced energy harvesting has exceptional output power density. • The harvester annihilates peak hydrodynamic loading on the tank wall like a baffle. [ABSTRACT FROM AUTHOR]

Liquid storage tanks are widely utilized in industrial areas and strategically very important to a country. Liquid sloshing in the tanks have a significant impact on tank design as well as its available volume. Ring baffles can be used to control liquid sloshing within a cylindrical tank. This paper conducted a series of shaking table tests on 21 scaled tank models excited by three real earthquake waves. In the baffled models, relative width and vertical position were the two design parameters. Based on the experimental test results, the sloshing wave height, acceleration and pressure stress of the tank wall have been summarized and analyzed. The effectiveness of the ring baffle in terms of reducing the liquid sloshing was confirmed through the test. When the relative width and relative vertical position respectively came within the range of 0.125 to 0.175 and 0.125 to 0.225, the sloshing wave height was generally well-suppressed, and meanwhile the acceleration of tank wall was effectively controlled. The horizontal ring baffle in the present study is considered as a simple and convenient measure to suppress the liquid sloshing with great application prospect. [ABSTRACT FROM AUTHOR]

Partially filled liquid-carrying tanks have been used in many engineering applications, such as ships, vehicle fuel tanks, rockets, and drink or petroleum tankers. Liquid sloshing is an exciting phenomenon that researchers are investigating because of its complex behavior specifications. In this study, the sloshing responses of a prismatic tank with the approximate volume of an automobile fuel tank under different laterally harmonic excitation amplitudes, baffle structures, filling rates, and different types of liquid were investigated numerically. The computational fluid dynamics method (CFD) was used to solve fluid dynamics equations, and the volume of fluid method was applied to simulate two-phase flow in the tank. A validation study was performed by a literature study. Later, the effect of large and small excitation amplitudes, filling rates and fluid types on sloshing behavior were investigated and comparatively analyzed in the tank system with various baffle types. [ABSTRACT FROM AUTHOR]

Fluid behavior in microgravity is different from that in normal gravity since surface tension and wetting are dominant in microgravity. In propellant tanks for future inorbit spacecraft, sloshing due to disturbance and a settling behavior from changes in acceleration must be understood for the design of the propellant supply system and attitude control system. As a target to understand the liquid behavior when the tank is accelerarated and decelerated in the second-stage rocket propulsion system, this study investigated the liquid behaviors in the cylindrical test tank via microgravity experiments and numerical calculations when the acceleration was applied in the axial direction in microgravity. The effects of acceleration direction (upward and downward), magnitude, and tank size on liquid behavior were clarified. As a result, it was shown that the experimental results agreed with the analytical ones when a large downward axial acceleration was applied, in which the liquid film on the solid wall became thicker. On the other hand, when the axial acceleration was small and the applied direction was upward, the breakage of the liquid film on the solid wall occurred in the numerical calculation, which was not observed in the experiment. From these results, it was shown that it was important to realize the thin liquid film on the solid wall surface by numerical calculations. Furthermore, based on the obtained knowledge, the effect of the liquid behavior under acceleration on the second-stage rocket propulsion system was considered. [ABSTRACT FROM AUTHOR]

The potential for sloshing reduction of passive, moving baffles with translational motion constrained by springs is investigated numerically in partially filled containers. Simulations are based on the level-set formulation, considering water as the liquid under study and a baffle made of aluminum; this selection allows for direct validation of the model against experimental and analytical data. Depending on the filling ratio V ∈ (0 , 1) , which simply measures the volume of liquid relative to the total container size, one can find an optimal spring stiffness K (V) that minimizes the kinetic energy and decay time of the sloshing response when subjected to a pulse-like acceleration. Results show that moving baffles significantly reduce sloshing compared to their fixed counterparts, with decreases up to 84.6% in decay time, τ d. Frequency analyses for different V reveal one or two resonances in the range of 0.1–1.5 Hz whose amplitudes are directly influenced (lowered) by K , analogous to the behavior of Tuned Mass Dampers. For potential applications, the selection of K should look for an adequate sloshing response over the entire range of V , and account for both quasi-static and harmonic excitation, conveniently weighted in accord with the expected operational loads. • Moving baffles are investigated for sloshing reduction in liquid containers. • The baffles' motion is constrained by spring elements with different K. • The fluid system is subjected to both quasi-steady and harmonic loads. • Several baffle designs are considered to improve sloshing performance. • The decay time of the kinetic energy is greatly reduced for all filling ratios. [ABSTRACT FROM AUTHOR]

• A coupled, monolithic ferrohydrodynamic interface-tracking model is introduced. • The equilibrium, stability, and modal analysis of axisymmetric interfaces is addressed. • The model is applied to the axisymmetric low-gravity magnetic liquid sloshing problem. • Numerical results are validated with microgravity experiments. A coupled ferrohydrodynamic interface-tracking model is introduced for the analysis of the equilibrium, linear stability, and modal response of magnetic liquid interfaces in surface tension-dominated axisymmetric multiphase flows. The incompressible viscous mass and momentum balances are solved together with the steady-state Maxwell equations by following a monolithic solution scheme. The method is fully implicit, allowing to reach a steady-state solution in a single time step. In addition, the time-dependent evolution of the interface subject to variable external inputs can also be simulated. The geometry is particularized for the study of the free surface oscillations of a ferrofluid in a cylindrical tank under the influence of an inhomogeneous magnetic field in microgravity. Five regions are used to discretize the simulation domain, which combines analytical and elliptic mappings. Magnetic-field-free results are validated by the literature. The modal response of the fluid-magnetic system agrees with measurements from the European Space Agency (ESA) Drop Your Thesis! 2017 The Ferros experiment and improves previous quasi-analytical estimations. This new framework of analysis can be applied to the study of a wide variety of microfluidic and low-gravity fluid systems. [ABSTRACT FROM AUTHOR]

A robust input command based on multiple steps for eliminating the residual vibrations of a multimode linear system is proposed. Only the system resonant frequencies are needed to determine the step magnitudes in the shaped command. The command duration is selectable to help in designing an optimum command that compensates between the reduction in the transient vibration, the enhancement in the command robustness, and the increase in the total maneuver time. The induced transient and residual sloshing oscillations of a suspended water-filled container are suppressed using the proposed command. The dynamics of the sloshing is numerically simulated using finite element method that accommodates the interactions between the fluid, structural, and multi-body dynamics. A short move time penalty is incurred with the price of significant reduction in the liquid sloshing. The performance of the shaped command to the system parameters and the robustness to their uncertainty are investigated. An improved robust input command in the presence of uncertainties in the cable length and water depth is also introduced. The effectiveness and excellence of the proposed command is demonstrated through a comparison with multimode zero-vibration input shaper and time-optimal flexible-body control. [ABSTRACT FROM AUTHOR]

In marine storage and transportation, the sloshing of liquid oxygen disturbs the thermodynamic equilibrium and induces stress on tank walls. Numerous problems are associated with the sloshing mechanism and demand a detailed investigation. In this study, a numerical model is developed by coupling the Eulerian framework and the algebraic interface area density (AIAD) method while considering the interphase drag force to investigate the thermal behavior of sloshing liquid oxygen. The effect of the sloshing frequency on the evaporation performance of liquid oxygen is studied. Moreover, anti-sloshing is conducted by employing a T-shaped baffle. The results show that the sloshing induced a vapor explosion phenomenon due to the invalidation of the surface impedance and thermal destratification to enhance free convection, resulting in rapid depressurization and increased evaporation loss. In addition, maximum evaporation loss occurred under the vapor–liquid coupling excitation condition. The T-shaped baffle has an excellent anti-sloshing effect because of the generating tip vortices and the enhanced shearing effect of the walls, which are regarded as motion damping factors. [ABSTRACT FROM AUTHOR]

Sloshing is a common flow phenomenon in liquid cargo tanks and has a great negative impact on the stability and safety of ship navigation. It is important to understand the sloshing process of tanks under the excitation of complex external conditions for the transportation of liquid cargo. In this paper, the sloshing characteristics of a liquid cargo tank are studied under the combination excitation conditions of roll and surge. The pressure distribution characteristics at different positions of the cargo tank are discussed, along with the influence of different excitation conditions on the pressure of the cargo tank. The results show that under the condition of combination excitation, the fluid sloshes along the diagonal direction of the tank, and the peak liquid height and peak pressure are located on the diagonal corner of the tank. The peak pressure at the lowest point on the diagonal of the tank is proportional to the amplitude of the roll angle and surge, and the change in roll angle amplitude has a significant impact on the pressure and liquid height at different positions. [ABSTRACT FROM AUTHOR]

Based on previous research on the small- scale supersonic flight experiment vehicle's liquid supplying system for bioethanol and LOX by pressurant gas, sloshing in the fuel tank has been shown to harm the flight of the vehicle by causing gas entrainment, which can fail the propulsion system. To solve this problem, we consider installing a device that can suppress the pressurant gas entrainment in the fuel tank. This device consists of a wire mesh that traps fuel in the supply duct by capillary force. In this study, this propellant management device (PMD) is examined based on the results of analysis and experiment. A liquid discharge experiment using the simulated propellant was carried out, as a performance verification of the PMD. This paper confirms the PMD's performance in preventing the entrainment of gas and supplying fuel at a maximum liquid discharge flow rate of 0.6 L/s in an actual flight model. [ABSTRACT FROM AUTHOR]

This research addresses the influence of the load characteristics, that is, frequency content and maximum acceleration, on the wall stresses of an anchored water storage tank. A low‐density polyethylene tank with a range of six different aspect ratios (water height to tank radius) was tested using a shake table. Eight sine excitations that cover the lowest free vibration frequency of the tank‐water system were applied. Additionally, two sets of five Ricker wavelet excitations were utilized. Each set represents potential earthquakes with a bandwidth between a low and a high dominant frequency. The experimentally determined maximum stresses and those obtained from calculations using a common spring‐mass model employed for seismic analysis of tanks were compared. The results reveal that the relationship between the excitation frequency and the wall stresses strongly depends on the sloshing behavior, especially when the frequency of loading is in the vicinity of the lowest free–vibration frequency of the tank–water system. When the frequencies are dissimilar, there is a proportional relationship between stress and the maximum acceleration of the excitation. The spring‐mass model was found to underestimate both the maximum hoop stress (for aspect ratios greater than two) and axial stress (for aspect ratios equal to 0.5). This occurs because is the spring‐mass model cannot capture, in all cases, the contribution of chaotic sloshing to wall stress. [ABSTRACT FROM AUTHOR]

Purpose: Sloshing is undesirable phenomenon and may invite instability in any type of tank partially filled with liquid. For a specially designed circular cylindrical container filled with an inviscid, incompressible, and homogenous liquid, if an annular baffle is attached to the outer cylinder wall in the annular region of the cylinder at some depth, the natural frequencies and the response of the liquid in the container undergo a drastic change. The purpose of this study is to report the sloshing modes and sloshing frequencies in the annular region of two coaxial vertical circular cylinders. Methods: An introduction of a baffle divides the liquid region into four. Boundary value problems are set up for the potential in each of these regions, and with the help of the matching conditions across the virtual interfaces, we set up a system of linear equations by solving which we determine the natural frequencies. Results and conclusions: The fundamental natural frequency of the liquid is determined for different width and positions of the baffle in addition to different configurations. It is observed that effect of baffle position on frequency is non-monotonic. It is also observed that when a baffle is placed nearer to the free surface, it has a greater significance on frequency. It is observed that frequency decreases with increasing baffle depth. The effect of the inner radius of the baffle on frequency is almost monotonic while with increasing inner radius of container, frequency increases monotonically. ANSYS is used to report the first modes of the sloshing. All our observations are supported by relevant graphs. [ABSTRACT FROM AUTHOR]

Sloshing flows of liquid natural gas (LNG) with multi-phase flow characteristics consisting of liquids and gases can affect the load conditions and structural response of cargo containment systems (CCS). The compressible properties of the sloshing flow can limit the maximum pressure, so a multi-phase fluid model is required to represent the sloshing physics. In this study, we identified a suitable numerical model to simulate the sloshing flow and structural strength evaluation based on the inhomogeneous fluid model. The computational fluid dynamics (CFD) is based on a Eulerian domain model, which is in turn based on the constant volume based finite element method (CVFEM) in a commercial Reynolds-averaged Navier–Stokes CFD code (ANSYS CFX). It includes the interphase momentum transfer between the liquids and gasses. The physics for the sloshing assessment were considered to identify the main aspects of the inhomogeneous multiphase model. For numerical analysis of the sloshing, we conducted a sloshing simulation on the experimental data of the model scale to examine the validity of the results. The velocity of the sloshing flow was extended to the real scale and applied to a local two-way fluid structure interaction (FSI) analysis model. Structural strength evaluation of the LNG CCS by sloshing flow was performed by FSI analysis. Through the example of structural response analysis of Mark III type CCS, the results were discussed and effectiveness of the proposed structural response assessment model by sloshing was reviewed. [ABSTRACT FROM AUTHOR]

A comprehensive experimental work is done to investigate sloshing dynamics in a partially liquid-filled baffled tank, equipped with a floating barge. An aspect ratio(hs/l, liquid depth, hs to length of tank, l) of 0.488 (above critical fill level), which corresponds to 75% fill level, is considered. The barge was subjected to regular wave excitations with a wave height of 0.1 m and frequencies ranging from 0.45Hz to 1.54Hz under beam sea condition. In addition, porous baffles are placed inside a rectangular tank to study its effectiveness in reducing the sloshing energy. Three different porosities of 15%, 20.2% and 25.2% at l/2 are considered. The effectiveness of baffles is explored and the salient results for a single porous baffle are discussed. It is learnt that the effect of baffles on sway and roll responses is significant, whereas it is insignificant on heave. Porous baffles are effective in suppressing the sloshing oscillation in the vicinity or at wave excitation, fw=f1, whereas the sloshing is amplified at fw=f2 and fw=f3 due to the resonance condition of modified natural frequencies. [ABSTRACT FROM AUTHOR]

This study proposes a new method for effectively and accurately simulating sloshing in a two-dimensional numerical tank. This technique uses the localized Trefftz method (LTM), a meshless numerical approach. Sloshing in a numerical tank is mathematically described as a space-time boundary-value problem rooted in potential flow theory. This occurrence is governed by a second-order partial differential equation and two nonlinear free-surface boundary conditions. In this study, the moving boundary problem undergoes discretization in time and space by using the LTM and the explicit Euler method, respectively. After discretization with the explicit Euler method, the elevation of the free surface is updated, and a boundary-value problem is generated at each time step. This boundary-value problem can be effectively examined using the recently developed LTM, which eliminates the need for complex meshing. Contrary to conventional methods, such as the method of fundamental solutions and the boundary element method, the LTM generates sparse matrices, allowing large-scale numerical simulations. Four numerical examples are presented to demonstrate the clarity and accuracy of the proposed meshless approach. • A localized mesh method for simulating the phenomenon of liquid sloshing in tanks has been proposed. • The LTM can generate sparse matrices, enabling more extensive and efficient numerical simulations. • Variations in the fluid's free surface under different excitation modes. • Four numerical examples validate the accuracy, stability, and effectiveness of the LTM. [ABSTRACT FROM AUTHOR]

Due to the complexity of fluid–structure interactions (FSI), the majority of studies in the literature dealing with the sloshing problem are restricted to rigid tanks. This paper is devoted to a numerical investigation of the liquid sloshing behavior in a flexible tank subjected to external loading. A numerical methodology is proposed, taking into account the FSI problem by coupling two open-source codes: OpenFOAM for the fluid and FEniCS for the solid, using the preCICE library, a free library for fluid–structure interaction. The Arbitrary Lagrangian–Eulerian formulation is used for the two-phase flow system to solve the Navier–Stokes equations in the fluid domain using the finite volume method. Simultaneously, the linear-elastic equation of the structure is solved using the finite element method. An implicit coupling scheme is considered at the fluid–structure interface. The numerical methodology is validated by the results given in literature for harmonic excitation at different frequencies. Subsequently, an analysis of complex external loading, such as Gabor wavelets and earthquake ground motion, is conducted to highlight the significant impact of the wall flexibility on sloshing, as well as the influence of hydrodynamic forces on the structure's deformation. The proposed coupling methodology is robust and effective, it can be applied to all types of liquids and materials. A dataset of one of the studied cases is given as a supplement to the paper (Kha et al., 2024). [ABSTRACT FROM AUTHOR]

When the acceleration of the liquid-filled container undergoes a step change, liquid sloshing is prone to occur. A sloshing linear dynamic model is put forward to predict the position change of center of mass of sloshing liquid. This modeling process uses a liquid static model and adds a time variable. The numerical simulation example finally verifies the feasibility of the mathematical model and shows that linear dynamic model has the ability to predict the displacement of the center of mass. [ABSTRACT FROM AUTHOR]

In the present paper, an improved multiphase weakly compressible smoothed particle hydrodynamics model for balancing the accuracy and stability of the long‐term simulations is proposed to model the forced liquid sloshing in a tank. The governing equations of the multiphase flow are discretized by considering the density discontinuity over the interface. To suppress the pressure oscillation, a previous density correction term suitable only for single‐phase problems is modified and incorporated into the discrete continuity equation to suit multiphase problems. The modified density reinitialization algorithm is implemented to calculate the pressure of the boundary particles, and the coupled dynamic solid boundary treatment (SBT) is employed to determine the rigid wall condition. For convenience, a numerical probe algorithm is also proposed to accurately measure the wave height. The present model exhibits a better numerical stability than the previous multiphase smoothed particle hydrodynamics model, and its results well confirm with the experimental data of the forced sloshing of liquid excited by swaying or rolling. [ABSTRACT FROM AUTHOR]

The problem of liquid sloshing exists widely in the fields of ships and ocean engineering. When the external excitation frequency is close to the natural frequency of the fluid in the tank, it is easy to produce violent sloshing and great forces, thus causing structural damage. Therefore, it is of great significance to study the effective method to control the impact of liquid sloshing. A numerical program was developed to study the sloshing problem in rectangular tanks with the topology optimization technique. In the numerical program the finite difference method was used to solve the homogeneous and incompressible 3D unsteady Navier-Stokes equations. The free surface was captured with the VOF/PLIC method and a topology optimization program based on the optimal control theory was applied to optimize the shape of baffles in the tank. The sloshing problem with given-shape double baffles and topologically optimized double baffles in the tank was calculated respectively and the kinematics and dynamic characteristics of the flow field with baffles were analyzed. The results show that, the topology optimization of the baffle shape brings better effects of sloshing suppression, which provides a new research idea for the sloshing problems in the fields of ships, ocean engineering and aerospace. [ABSTRACT FROM AUTHOR]

Smoothed particle hydrodynamics (SPH) is a meshfree, Lagrangian, particle method, which combines the advantages of Euler and Lagrangian method and has special advantages in simulating violent non-linear fluid–structure interaction problems. In this study, an improved SPH method is used to simulate four fluid–structure interaction cases. Firstly, the violent flow in the mould filling process is simulated to validate that the SPH model can obtain accurate flow patterns with any complex solid boundaries. Secondly, the dam-break flow against a vertical wall is simulated, and the pressure curves are compared with the experiment. Then liquid sloshing problems under different external excitations are simulated, and the complex coupling characteristics can be captured. Finally, the interactions between fluid and floating bodies are researched. The obtained numerical results show good agreement with the results from other sources, and clearly demonstrate the effectiveness of the presented SPH method in modelling fluid–structure interaction problems. [ABSTRACT FROM AUTHOR]

Tank sloshing in a liquid cargo ship will cause instability or even overturning of its carrier if the external wave frequency is close to the natural frequency of the tank. The inherent damping of a tank without inner structures has been found to be insufficient for suppressing violent sloshing motion. A variety of damping plates have been designed to increase the inherent damping of the tank. Of them, a horizontal perforated plate (HPP) has been proved to be effective for dissipating energy in a swaying tank through experiments. In this study, the sloshing problem in a tank with an HPP under swaying and rolling excitation is analytically studied based on the potential theory. The quadratic pressure loss boundary at the perforated plate is adopted, and the matched eigenfunction expansion method (MEEM) with iterative calculations is used to develop the analytical model. Based on the different porosities and submerged depths of the plate, both the free surface elevations and the hydrodynamic coefficients are carefully examined. The results give a better understanding in the effect of the inner HPP on the sloshing motion in the ship tank. [ABSTRACT FROM AUTHOR]

An isogeometric boundary element method (IGA-BEM) based on the non-uniform rational B-splines (NURBS) is firstly performed to investigate the liquid sloshing in axisymmetric tanks with the porous baffles. The proposed method can completely maintain the advantages of the BEM that only the boundary of a domain requires discretization. By applying the NURBS basis functions it can exactly describe the geometry of the boundary. Meanwhile, it can also be obtained better solution field approximation at the domain boundary. Furthermore, as to the axisymmetric geometries of the containers considered in this paper, the 3-D liquid sloshing problems can be effectively reduced to 2-D ones on half of the cross-sections of the containers, which can significantly increase the computational efficiency. Meanwhile, the zoning method is employed in this paper to treat the arbitrary mounted porous baffles, and the Laplace equation is utilized as the governing equation of the potential flow model by assuming the fluid motion to be inviscid, irrotational and incompressible. Additionally, the weighted residual method together with the Green's theorem is applied to develop the BEM integral equation. The natural sloshing frequencies and dynamic sloshing forces solved by the proposed method are compared with the available literatures and the traditional boundary element method (BEM). Good agreements are observed in the comparisons between numerical results and those of the existing literatures. And higher accuracy and convergence can be achieved by the proposed IGA-BEM method with significantly fewer nodes than the traditional BEM. Moreover, spherical tanks with the coaxial hemispherical, wall-mounted conical or surface-piercing cylindrical porous baffle, ellipsoidal tanks with spheroidal or surface-piercing cylindrical porous baffle, and the toroidal tank with tubular porous baffle are considered to investigate the effects of the porous-effect parameter, radius, length, height, horizontal and vertical semi-axes of the porous baffle on the sloshing characteristics (i.e. dynamic sloshing forces and surface elevations). The results show that the surface-piercing cylindrical porous baffle offers more noticeable suppression on sloshing response than the hemispherical and spheroidal porous baffles. Changing the radius of the tubular porous baffle has almost negligible effect on the sloshing force acting on the toroidal tank. The excitation frequency corresponding to the maximal value of sloshing force can be altered evidently by changing the porous-effect parameter of the porous baffle. In addition, choosing reasonable porous-effect parameter, radius, horizontal semi-axes and relatively larger length, height as well as vertical semi-axes for the porous baffles yields considerable suppression on the sloshing response. [ABSTRACT FROM AUTHOR]

This paper presents a parametric study on tuned liquid sloshing damper (TLD), which has been carried out theoretically and experimentally. Theoretically, the governing differential equation of the equivalent mechanical model is solved using Fourier expansion-based differential quadrature method. The obtained solution shows good agreement with the experimental results. Experimentally, a simple test rig is designed and constructed in order to acquire free vibration of a pendulum like platform with an attached liquid slosh damper. Different parameters, i.e. the liquid filling ratio, the liquid viscosity and the tank shapes, are studied theoretically and experimentally in order to investigate the damping capacity of the supplementary damper. It can be concluded that Fourier expansion-based differential quadrature method has been reliable and efficient in solving the proposed problem, as the liquid viscosity increases damping capacity increases for all shapes of the tanks, the rectangular tank is the most effective shape on damping capacity with respect to the considered shapes. Filling ratio plays an important role in controlling both of settling time and damping coefficient, where 16% filling ratio provides the most damping capacity. Generally, the TLD has been more effective for structures with low damping ratios where structural acceleration decreases with the introduction of the TLD. [ABSTRACT FROM AUTHOR]

The coupling effect between the internal fluid sloshing and the box sway motion under irregular wave action is studied in this work. For describing external wave and internal sloshing actions, a hybrid numerical method combining linear potential flow and viscous flow is adopted. Numerical simulations show that coupling sloshing action plays an important role around sloshing natural frequencies. The significant resistant and enhanced actions can be observed at the frequencies around sloshing natural frequencies in regular waves. However, the above coupling effect approaches weak under irregular wave actions. The phase relation between the internal sloshing forces and external wave forces in regular waves cannot be found under irregular wave actions, which is the main reason for the decreased coupling sloshing effect. In all, the sway motion responses between irregular and regular wave actions show evident different behaviors from each other. • The coupling effect is most significant near the sloshing natural frequency. • The sway motion responses between regular and irregular wave actions show evident different behaviors from each other. • The phase relationship between the wave force and the sloshing force is crucial for the coupling effect. • The components near the natural frequency of the wave force and the sloshing force are out-of-phase. [ABSTRACT FROM AUTHOR]

The sloshing behavior of two-layered liquid in a rectangular sloshing tank with a vertical porous baffle under sway excitation has been investigated using both analytical and numerical methods. The analytical model is developed using the matched eigenfunction expansion method in conjunction with linear potential flow theory. The existence of vertical porous baffle results in energy dissipation by applying the boundary condition that pressure drop across the baffle is proportional only to the quadratic drag term. For comparison, numerical simulations are conducted using computational fluid dynamics (CFD) with unsteady, implicit, and incompressible fluid equations. The study explores the effects of the liquid density ratio, the baffle's porosity, and its submergence depth, on various parameters including the free surface and interfacial elevations, hydrodynamic force on the tank surface, and horizontal force on the baffle. The trends observed in the analytical model align well with the CFD results and experiments. It is found that a fully submerged vertical porous baffle with a porosity close to P = 0.1 leads to stable and less dynamically active sloshing behavior in a two-layered liquid tank. • Studied two-layered liquid sloshing with porous baffle under sway excitation. • MEEM (analytical) and RANS (CFD) models are used for investigation. • Density ratio affects free surface slightly, and interface strongly. • Fully submerged baffle with 0.1 porosity mitigates sloshing effectively. [ABSTRACT FROM AUTHOR]

Sloshing is a phenomenon where a partially filled tank is exerted into various environmental sea conditions, such as wave and wind. Sloshing in a tank of liquefied natural gas carrier can lead to structural damage of tank structures and motion instability of the carrier. Thus, sloshing analysis needs to be conducted beforehand to minimize the risk of damages. This paper presents experimental and numerical study on sloshing phenomenon in a prismatic membrane tank model under unidirectional excitation with 30% water filling condition. A regular wave motion stimulated by the linear actuator was applied to the model tank and recorded by a video camera. Meanwhile, OpenFoam software was used to simulate the sloshing numerically in a volume of fluid method based on Navier-Stokes theorem. The sloshing patterns and free surface elevation in the prismatic membrane model tank, with the same input amplitude and frequency, were investigated for both cases. Both experimental and simulation results showed reasonable agreement on the sloshing profile, while the internal free surface elevation in the closed domain indicated a deviation with maximum absolute error of 4.9 cm. [ABSTRACT FROM AUTHOR]

Abstract In the present study we perform shake table experiments to study the fluid structure interaction effects between the sloshing liquid and the internal structure. A partially filled storage tank is systematically subjected to (i) horizontal (ii) vertical and (iii) seismic excitations. To start with, forced horizontal excitations are imposed by varying the amplitude of excitation ranging from 0.001 L to 0.0075 L , where, L is the tank length. As the amplitude of excitation is increased, sub-harmonic wave features were observed at the wave crests, which indicate the presence of higher slosh modes. The resulting resonant free surface oscillations are validated against available theoretical and computational studies. Furthermore, the tank was subjected to vertical harmonic excitations at n th slosh frequency (ω n), where, n = 1, 2, 3 and 4 covers first four sloshing modes. The excitation frequency (Ω n = ω n ∕ ω v) of 0.5 and the corresponding forcing amplitudes (κ v) are chosen such that, the combinations were with in the unstable range of Matheiu's instability diagram. For higher modes of vertical excitation, the free surface oscillations were found to be better damped. A detailed study of flow visuals, free surface fluctuations, dynamic pressure data, power spectral densities, structural responses etc reveal the nature of coupling with the container wall and the circular cylinder. The shake table is further programmed to simulate the well known El Centro earthquake excitation, where the storage tank is imposed with horizontal as well as combined horizontal and vertical components of excitation (at 50% of actual amplitude) to investigate the fluid structure interaction effects. When the partially filled storage tank is subjected to seismic excitation, spiky jet like features were observed over the free surface. [ABSTRACT FROM AUTHOR]

Accurate prediction of the vibration characteristics of the sloshing motion is essential for the analysis and design of liquid storage tanks subjected to base motion. The virtual mass method is a computationally efficient approach to determine the hydrodynamic forces generated by incompressible and inviscid fluids in accelerated containers since the virtual mass method involves meshing of the fluid boundaries rather than the entire fluid domain. Hydrodynamic actions of the sloshing liquid are taken into consideration by coupling a virtual fluid mass matrix to the structural points on the wetted regions of the tank wall. Analysis of the free surface displacements of the contained liquid can be carried out using the virtual mass method and this paper focuses on the application of the virtual mass method for the analysis of the vibration frequencies and mode shapes of the sloshing modes in rectangular and cylindrical liquid storage tanks. Firstly, the theoretical background for the analytical solution of the mode shapes and modal frequencies is presented for rectangular and cylindrical liquid tanks. This is followed by the description of the procedure used to apply the virtual mass method to obtain the sloshing modes and mode shapes of the contained liquid. The effects of various surface mesh topologies on the predicted vibration characteristics are compared with the analytical solutions as well as the results of an experimental study conducted on scaled rectangular and cylindrical containers mounted on a shake table. [ABSTRACT FROM AUTHOR]

Sloshing of the contained liquid is an important issue, which needs to be dealt with in the design of moving liquid storage tanks, such as fuel tanks subjected to earthquakes. Numerical methods such as the finite element method or smoothed particle hydrodynamics are commonly used to analyze the sloshing response of liquids in the design of liquid storage containers. The analysis results obtained from numerical methods are usually validated through the comparison of free surface displacements obtained from laboratory tests conducted on scaled tank models. However, the equipment required for measurement can be quite costly and the setup of the measurement system for moving containers can be a tedious process. In order to simplify the measurement setup and reduce the associated cost, we propose a measurement system based on morphological image analysis using a stationary HD camera. In order to verify the validity of the proposed method a shaking table test was conducted on a transparent prismatic liquid tank subjected to a simulated earthquake base motion. The liquid tank was filled with colored water to facilitate image analysis. The video record of the experiment was processed by the proposed algorithm implemented in the MATLAB environment to measure free surface displacements directly on the wall of the tank. The free surface displacements obtained from the video record by automated image analysis were congruent with the manual measurements conducted on the individual video frames. [ABSTRACT FROM AUTHOR]

Abstract Annular reinforced concrete ribs, or baffles, have been used effectively for suppressing liquid sloshing due to earthquake motion in large cylindrical tanks. Meanwhile, these added structural elements may change the structural characteristics of tanks and negatively affect their seismic behavior. In this paper, effects of baffles on the seismic behavior of concrete cylindrical tanks are evaluated. Regarding aspect ratio, three types of tanks including short, medium and tall structures are examined under 9 earthquake ground motions. Seismic fragility curves are calculated for liquid sloshing, vertical crack width due to the tensile hoop force, and bending moment of the tank wall at the base. The results display the structural benefits and costs of baffles in liquid storage tanks. While use of baffles largely decreases the sloshing wave height, it results in a minor increase of the vertical crack width and the base bending moment of the tank wall. The benefit of the decreased sloshing height seems to govern the cost of the minor increase of the mentioned responses. Highlights • Seismic fragility curves are calculated for tall, medium, and shallow tanks, having annular baffles near the top of liquid. • Fragilities including fluid overflow, vertical cracking, wall bending and overturning are presented. • While use of baffle decreases fragility of overflow to a large extent, it slightly increases the structural fragilities. • Annular baffle makes seismic fragility of tanks to become almost identical for both shallow and tall tanks. [ABSTRACT FROM AUTHOR]

The present study aims to investigate the effect of liquid sloshing of inner tanks on the dynamic responses of an underwater soft yoke mooring system. For this purpose, inner tanks with different filling levels were examined under different external wave loads in towing tank experiments. The specified waves generated by a piston-type wavemaker are validated. It is found that the dynamic response of the new underwater soft yoke mooring system is sensitive to the inner tank sloshing and the external wave load type and the effect become more significant when the wave becomes more turbulent. Besides, the filling depth of the inner tank plays a vital role on the dynamic response of the mooring system. Particularly, a significant increase in the force acting on the mooring legs was found when the floating structure was configured with two inner tanks. [ABSTRACT FROM AUTHOR]

Abstract Hydrodynamics of an anti-sloshing technique using floating foams in a rectangular liquid tank is investigated. A series of experiments are conducted. An analytical potential-flow solution is derived to help explain the experimental observations. Effects of various layers of floating foams on both the wave profiles and dynamic pressure histories in sloshing tanks are analyzed. It shows that even a single layer of floating foams can help reduce the sloshing amplitude due to energy dissipation. If multiple layers of floating foams are further applied, the sloshing amplitude can be further reduced. The amplitude of dynamic pressure in the tank is also found to decrease as the number of foam layers increases. Besides, anti-sloshing effects of floating foams in tanks of different depths are discussed. Floating foams are found to work more efficiently for larger amplitude sloshing waves. Highlights • An anti-sloshing technique based on floating foams is introduced. • Hydrodynamics of sloshing tanks with floating foams is investigated. • Both analytical and experimental investigations are carried out. • Effects of floating foams on wave elevation and sloshing pressure are discussed. [ABSTRACT FROM AUTHOR]

Abstract The screen-affected sloshing with a wide excitation frequency including the third and the fifth mode frequencies were investigated experimentally by varying solidity ratio, slot size, location and slat screen number. The maximum surface elevation decreases as solidity ratio increases when frequencies are not changed obviously due to screens inside tanks. Effects of slat screen on sloshing are related to solidity ratio and frequency. One vertical screen fails in significantly suppressing sloshing excited by the third mode horizontal excitation. Two slat screens can effectively reduce sloshing excited by horizontal excitation with a relatively wide frequency range and the recommended screen positions are presented according to excitation frequencies. Sloshing reduction does not always apparently increase as screen number increases under the screen positions specified in experiments. Sloshing amplitude with two slat screens may be greater than that with one slat screen located at tank centre when frequency is near the fifth-mode or third-mode frequency depending on two screens positions. Though wave amplitudes reductions are a little more noticeable in tank with 5 mm slot size screen than those in tank with 50 mm slot size screen, wave frequency components with 5 mm slot size screen are much simpler than those with 50 mm slot size screen. [ABSTRACT FROM AUTHOR]

Abstract Three-dimensional (3-D) ground-supported cylindrical and rectangular rigid liquid storage tanks filled with water and subjected to seismic base excitation are investigated using finite element method (FEM). The analyses of the tanks are carried out using coupled acoustic-structural (CAS) and coupled Eulerian-Lagrangian (CEL) approaches of the FEM using Abaqus®. The CAS approach based on linear wave theory and the CEL approach based on non-linear wave theory are used here to study the fluid-structure interaction (FSI) behavior of the tanks. Sloshing displacement, impulsive, convective, and total hydrodynamic pressures are investigated for varying geometries of the tanks. The small amplitude sloshing and hydrodynamic pressure responses are compared between the two FE-based, CAS and CEL approaches. The results obtained from the present FE-based analysis approaches are found to be in close agreement with the experimentally obtained seismic response in the 3-D cylindrical and rectangular tanks subjected to seismic ground motions. The ratio of peak sloshing height (h) to liquid height in the tank (H L) obtained in the cylindrical tank using the CAS approach is 0.0425 and that by the CEL is 0.039, whereas for rectangular tank it is 0.060 by the CAS approach and 0.046 by the CEL approach; thereby, signifying relatively small sloshing amplitude response. It is concluded that the non-linearity of the sloshing wave displacement does not play a significant role while calculating the hydrodynamic pressure distribution on the rigid tank walls. Highlights • FE simulations by coupled acoustic-structural (CAS) and coupled Euler-Lagrange (CEL). • Small amplitude sloshing displacement and hydrodynamic pressures in rigid tanks. • Dynamic analysis of cylindrical and rectangular rigid tanks for seismic excitations. [ABSTRACT FROM AUTHOR]

Abstract In this study, sloshing response of liquid is investigated in partially filled rectangular tanks subjected to earthquake ground motions. To verify the numerical modeling, shaking-table tests were carried out in sub-scale tanks for different excitation amplitudes, frequencies and fill water levels. Using the calibrated models, nonlinear numerical simulations were performed for practical tanks under different horizontal and vertical near fault excitations. The results express that the liquid pressure induced on tank under vertical seismic loading can be increased especially in near-field earthquakes, however, its effect on sloshing wave height is negligible. Also the results for different tanks under both horizontal and vertical earthquakes show that free surface vertical displacement depends on the spectral response acceleration at the first fundamental period of sloshing behavior. Moreover, the induced pressure is strongly influenced by the earthquake peak ground acceleration and also by the spectrum response acceleration at the first sloshing mode. Highlights • Experimental tests in sub-scale tanks for different excitations and fill water level. • The effect of vertical seismic loading on sloshing wave height is negligible. • PGA and spectrum acceleration at first sloshing mode influence on walls pressure. • Spectral acceleration of first sloshing mode affects vertical displacement of wave. [ABSTRACT FROM AUTHOR]

Purpose The purpose of this paper is to apply the Peridynamic differential operator (PDDO) to incompressible inviscid fluid flow with moving boundaries. Based on the potential flow theory, a Lagrangian formulation is used to cope with non-linear free-surface waves of sloshing water in 2D and 3D rectangular and square tanks.Design/methodology/approach In fact, PDDO recasts the local differentiation operator through a nonlocal integration scheme. This makes the method capable of determining the derivatives of a field variable, more precisely than direct differentiation, when jump discontinuities or gradient singularities come into the picture. The issue of gradient singularity can be found in tanks containing vertical/horizontal baffles.Findings The application of PDDO helps to obtain the velocity field with a high accuracy at each time step that leads to a suitable geometry updating for the procedure. Domain/boundary nodes are updated by using a second-order finite difference time algorithm. The method is applied to the solution of different examples including tanks with baffles. The accuracy of the method is scrutinized by comparing the numerical results with analytical, numerical and experimental results available in the literature.Originality/value Based on the investigations, PDDO can be considered a reliable and suitable approach to cope with sloshing problems in tanks. The paper paves the way to apply the method for a wider range of problems such as compressible fluid flow. [ABSTRACT FROM AUTHOR]

Sloshing is a complex nonlinear dynamic phenomenon which has a significant influence on the stability of structure–fluid systems. In this study, the dynamic equation of sloshing based on Hamilton principle is established and linearized into a state space equation. Considering the uncertainty of the system, a robust H infinite guaranteed cost control method is proposed to mitigate the response of fluid wave height to horizontal acceleration of the tank body. Simulation results are given to demonstrate the closed-loop performance of the nonlinear dynamic modeling and linear optimal control method. [ABSTRACT FROM AUTHOR]

Traditional methods for analyzing the dynamics of fluid-carrying vehicles such as pendulum or mass–spring models do not yield accurate results, thus seeking new methods for investigating the dynamics of these vehicles is desirable. The objective of this study is to find a new methodology for handling the dynamics of such systems. In this paper, an algorithm is proposed by which a data bridge is implemented between two commercial software programs such that a coupled simulation of the carrier and fluid dynamics is achieved. Unlike alternative mechanical models, the most important feature of this method is its validity during all events regardless of carrier position and orientation. Finally, this approach is validated by experiments. Experimental results are in excellent agreement with simulations. In addition, unlike existing algorithms, the proposed algorithm is numerically stable. [ABSTRACT FROM AUTHOR]

Abstract A modular floating concept for oil storage is proposed. The concept is composed of modular floating tanks and barges. The floating tanks are self-stable and designed for storage of oil and hydrocarbon material. The barges are connected together and moored by mooring dolphins. Mooring system is designed between barges and the tanks enclosed by the barges. An innovative mooring system that consists of several mooring ropes besides the fender system is proposed and investigated in this study. The mooring ropes are stretchy and can carry the mooring loads in all the loading and environmental conditions. Single floating tank is investigated under different filling levels, i.e. empty, full and partially filled conditions. It is assumed in this study that the barges are fixed, and multi-body hydrodynamic interaction is neglected. Linear and nonlinear mooring rope properties are investigated. Failure condition of one of the mooring rope is also considered. Wind, wave and current load effects under 100-year storm are also investigated, as well as the uncertainty analysis in terms of viscous effects. Highlights • Dynamic response analysis of floating storage tanks, under operational and extreme conditions. • Innovative mooring system design and analysis for the floating storage tanks. • Partial loading condition with sloshing effects. • Linear, nonlinear mooring stiffness, failure condition. • Uncertainty analysis due to viscous effects. [ABSTRACT FROM AUTHOR]

In this paper, numerical simulations of nonlinear sloshing in rectangular tanks are presented. Model implementations in the open source software reef3d are tested, and the results are compared with experimental data from three different conditions. The interface location is compared for both linear and nonlinear sloshing. The nonlinear sloshing is simulated in both two-dimensional (2D) and three-dimensional (3D). Video images from the SPHERIC project are compared with simulations for the interface. A condition with lateral wave impacts in sloshing, with a frequency close to the natural frequency of the first mode, can be found in this case. The numerical model is solving the Reynolds-averaged Navier-Stokes (RANS) equations with the k-ω turbulence model. The level set method is used to capture the interface. Higher order discretization schemes are implemented to handle time-evolution and convective fluxes. A ghost cell method is used to account for solid boundaries and parallel computations. It is found that the limiting factor for the eddy-viscosity has significant influence in the nonlinear sloshing cases. As the sloshing becomes more violent, the increased strain at the gas-liquid interface overproduces turbulence energy with unrealistically high damping of the motion. Three-dimensional simulations show slightly better comparison than 2D. Due to nonlinearities and small damping, the time to reach steady-state may take several cycles. The last case shows promising results for the global motion. As expected, the breakup of the liquid surface makes it difficult to resolve each phase. But overall, the numerical model predicts the sloshing motion reasonably well. [ABSTRACT FROM AUTHOR]

Laboratory experiments were conducted to study porous baffle effects on reducing liquid sloshing in a rectangular tank on a six-degrees-of-freedom motion simulation platform. The porous baffle that was a material layer made from spherical particles fully filled into a cage made of perforated stainless-steel plate was proposed. The free surface wave height and the impact pressure on the wall were recorded in laboratory experiments of liquid sloshing in a horizontally excited rectangular tank. These experiments were used to validate the porous media model in OpenFOAM. The OpenFOAM was then employed to simulate sloshing in a rectangular tank with a porous baffle to reveal the sloshing damping mechanism of the porous baffle by changing the external excitation frequency. The results show that the porous baffle is more effective in suppressing impact pressure at a high excitation frequency. • Porous baffle that was a material layer made from particles fully filled into a cage made of perforated plate was proposed. • Laboratory experiments were conducted to study porous baffle effects on reducing liquid sloshing. • The numerical model of porous media in OpenFOAM was validated against the present experimental data. • Numerical study on damping effects of the porous baffle was presented. [ABSTRACT FROM AUTHOR]

A series of laboratory experiments are conducted to investigate liquid sloshing in a rectangular tank with a vertical baffle of varying elasticity under horizontal excitations. Image processing techniques are introduced to track baffle displacement, as well as to identify the free surface and the bubble. Dye visualization is employed to reveal the vortex behavior around the baffle. The air entrainment mechanism, including jet impinging, air cavity formation and deformation, and turbulent mixing, is analyzed. Moreover, the study investigates the effect of baffles with different stiffness on suppressing liquid sloshing across a wide range of excitation frequencies. The results show that the peak frequencies of the maximum free surface elevation-frequency curves correspond to the first natural frequency of fluid, the sub-resonance frequency, and the wet natural frequency of the elastic baffle. It is also found that the elastic baffle can effectively reduce liquid sloshing within a certain frequency range and balance the slamming impact both on the wall and the baffle, providing promising prospects for its practical applications. [ABSTRACT FROM AUTHOR]

Abstract Integrated dynamic responses of FLNG system in side-by-side offloading operation are investigated numerically and experimentally in this paper. A numerical code is developed based on potential flow theory to predict the interactions between connected vessels' motions and liquid sloshing in the time domain. The impulsive response function (IRF) method is adopted in the resolution for 6 DOF vessels' motions, nonlinear sloshing in liquid tanks is solved using boundary element method (BEM), and connection system including hawsers and fenders is numerically modeled as linear response system. A series of model tests are conducted to validate the feasibility of the numerical code. Hydrodynamic interaction between the vessels and shielding effects under different wave directions are analyzed; sloshing effects on the vessels' motions and on the loads of connection system are investigated; the sensitivities of the vessels' motions and loads to connection system stiffness are discussed. It is found that the vessels' motions are significantly affected by the hydrodynamic interactions between vessels and sensitive to wave directions for shielding effects. The radiation forces of the adjacent vessel tend to amplify vessel's motions and LNG carrier is more likely to be affected by FLNG's radiation forces for their difference in displacement. In addition, compared with solid loading condition, liquid loading vessel tends to have decreased natural roll frequency and have increased sway motions in the frequency region that higher than the natural sloshing frequency. The two sloshing responses peaks appear in the natural roll frequencies and natural sloshing frequencies, which are respectively mainly excited by vessels' roll and sway motions. Besides, in low fill conditions, the sloshing loads contribute to larger sway motions in low fill conditions for the natural sloshing frequencies are closer to the main response frequency region of vessels. Sloshing nonlinearity gets obvious in the conditions with low fill conditions and large wave amplitude, while the motion responses of vessels have slight nonlinearity with the increases of sloshing nonlinearity when no violent sloshing with wave break is excited. Furthermore, small stiffness of the connection system has slight influences on the vessels' motions, and resonant motions can be excited when the natural frequency of the connection system located in the wave frequency region. Highlights • A numerical code is developed to predict the integrated dynamic responses in side-by-side offloading FLNG system. • Experimental tests are conducted to validate the numerical code. • Comparative studies are carried out to investigate the coupling mechanism. • The effects of filling levels and wave directions on FLNG performances are investigated. [ABSTRACT FROM AUTHOR]