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This paper presents a procedure for evaluating the structural safety of Liquefied Natural Gas (LNG) Cargo Containment System (CCS) against sloshing load by comparing the results of linear and nonlinear dynamic structural strength analysis with those of verified reference vessels. This comparative procedure indirectly considers (1) limitation of implementing real physical phenomena in model experiments including the Froude scaling method, density ratio, etc., (2) assumptions in statistical analysis for calculating design loads, and (3) complicated effects not implemented in nonlinear dynamic analysis such as phase transition between liquid and gas, hull deflection, and the detailed geometry of the CCS, among others. The uncertainties in sloshing model experiments and statistical analysis can be addressed by introducing the pressure correction factors, which make the linear design loads of the reference vessel satisfy the CCS's capacity. Finally, the structural nonlinearity, which was not accounted for in the nonlinear dynamic analysis, can be taken into consideration through a comparison of the usage factors from nonlinear dynamic analysis. To apply the proposed structural assessment procedure, the GTT NO96 series were selected and applied to two failure modes. In the application of this procedure, the Triangular Impulse Response Function (TIRF) method was adopted, to efficiently calculate numerous linear dynamic structural strength analyses required for Dynamic Amplification Factor (DAF). Through this application applying larger sloshing loads to the reinforced NO96 CCS of the target vessel compared to the reference vessel, the feasibility of this procedure was shown. [ABSTRACT FROM AUTHOR]

Owing to the increasing g lobal demand for natural gas, the construction of liquefied natural gas (LNG) carriers has become a key trend in the shipbuilding market. In the design of membrane-type LNG carriers, a sloshing analysis is crucial for cargo containment systems (CCSs). In this study, structural responses due to impulsive sloshing loads were observed, including the effects of hydroelasticity and the test medium. To this end, the structural responses were first observed with and without hydroelastic coupling between the liquid and structure. When fluid–structure coupling is considered, a finite element analysis is performed for the integrated structure of the hull and CCS. This method was then applied to evaluate the capacity and safety of the inner hull structures of actual LNG vessels in cases where different sloshing pressures occurred owing to the different liquid–gas media. The structural capacity was evaluated using the utilization factor (UT). The results confirm that the effects of the hydroelasticity, density ratio, and phase transition of the experimental medium are essential for the evaluation of the structural responses of LNG CCSs. [ABSTRACT FROM AUTHOR]

Historical seismic events have repeatedly highlighted the susceptibility of above-ground liquid storage steel tanks, underscoring the critical need for their proper design to minimize potential damage due to seismic forces. A significant failure mechanism in these structures, which play essential roles in the extraction and distribution of various raw or refined materials—many of which are flammable or environmentally hazardous—is the dynamic buckling of the tank walls. This study introduces a numerical framework designed to assess the earthquake-induced hydrodynamic pressures exerted on the walls of cylindrical steel tanks. These pressures result from the inertial forces generated during seismic activity. The computational framework incorporates material and geometric nonlinearities and models the tanks using four-node shell elements with two-point integration, specifically Belytschko shell elements. The Arbitrary Lagrangian–Eulerian (ALE) method is employed to accommodate substantial structural and fluid deformations, enabling a full simulation of fluid–structure interaction through highly nonlinear algorithms. Experimental test data are utilized to validate the proposed modeling approach, particularly in replicating sloshing phenomena and identifying stress concentrations that may lead to wall buckling. The study further presents results from a parametric analysis that varies the height-to-radius and radius-to-thickness ratios of a typical anchored flat-bottomed tank, examining the seismic performance of this common storage system. These results provide insights into the relationship between tank properties and mechanical behavior under dynamic loading conditions. [ABSTRACT FROM AUTHOR]

Sloshing in coaxial shells partially filled with liquid is investigated using reduced boundary element method. Conical shells are considered as storage tanks. An ideal and incompressible fluid is assumed in the shells. The spectral boundary problem for the liquid vibrations in rigid shells is solved. The results demonstrate the high accuracy of the presented approach. [ABSTRACT FROM AUTHOR]

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 presents design method for a tuned liquid damper (TLD) to improve the stability of measurement system based on a spar buoy. Firstly, a TLD was designed utilizing the double-partition hull structure of spar buoy, and the theoretical natural sloshing frequency for this design was calculated. Next, an experimental study was conducted to verify the theoretical calculations. The experimental results showed that the natural sloshing frequency increased with the height of the fluid free-surface, and the values are in close agreement with the theoretical calculations. Finally, the TLD was installed to a free-drifting structure at sea, and the dynamic behavior reduction effect was experimentally verified. The results showed that the behavior of the structure is significantly reduced after the TLD is installed, especially for the behavior above 4 cm. The main contribution of this study is the integration of a TLD into the existing structure of the spar buoy, which enhances stability without compromising buoyancy. However, this approach is limited by the shape and volume constraints of the TLD, making it less effective across all wave-induced frequencies. Further research is required to extend its applicability to a broader range of maritime conditions. [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]

Sloshing of liquefied bulk granular cargoes weakens the stability of cargo carriers when at sea. Using the horizontal rectangle baffle is a promising way to restrain its sloshing motion. But the location height and optimal baffle area rate to achieve a better anti-sloshing effect should be studied first. The discrete element method was adopted to establish the simulation model, and the direct shear test was used for verification. Through the static tilt tests, the definite relationship between the effects of moisture content on cargo motion and particle friction coefficients was acquired. Then, liquefied cargo motion in a cargo hold without baffles and with one and two pairs of horizontal baffles was simulated. Based on variations in the cargo gravity center offset and the sloshing-induced force on the cargo hold, the anti-sloshing effect of different settings of the baffles was compared. Results show that the baffles have the ability to restrain cargo sloshing, and this is important for sea transportation safety. The anti-sloshing effect is better when the baffle plane is right on the cargo top surface compared to the other location heights. Further, there is an optimal length–width combination, e.g., a single baffle plane with a length of 0.26 L and a width of 0.46 B, at which a better anti-sloshing effect could be achieved with the smallest baffle area rate. This study could be useful for the practical application of horizontal baffles for bulk granular cargo carriers. [ABSTRACT FROM AUTHOR]

Jet fuel in aircraft fuel tanks moves due to acceleration resulting from maneuvers. The movement mentioned here directly impacts the Center of Gravity (CG). The aircraft's flight mechanics are significantly affected by the deviation of its CG on the aircraft body, and excessive deviation is undesirable. Preventing CG deviation is achieved by designing various baffles within the fuel tank. In this study, design details of the baffles were investigated with the help of an artificial neural network (ANN) model, 1D simulations, and computational fluid dynamics (CFD) calculations. The 1D simulations, which model the fuel movement, were used to understand the general behavior of the fluid in the tank. CFD calculations simulating turbulent fluid flow in three dimensions were used to confirm the results of the 1D simulations and provide more detailed information. A simulation set is created utilizing five parameters: barrier usage, volume fraction, cutout diameter, number of cutouts, and cutout location. Compared to the barrierless design, the barrier usage as a parameter changes either on baffle number 1, 3, and 6, or on baffle number 2, 4, and 7. The fuel volume fraction parameter accounts for 30%, 45%, and 60% of the interior volume. The diameters of the cutout holes vary between 30 mm and 156 mm and are used as categorized among the baffles. Cutout holes are applied on baffles in single, twin, and triplet forms and their locations are subjected to a divergence of either −20 mm or +20 mm from the z-axis. Based on these parameters, the maximum deviation and the retreat time of CG constitute the output parameters. The importance of the input parameters on the outputs was obtained with the help of an ANN algorithm created from the results of all possible combinations of a sufficient number of 1D simulations. To obtain more detailed results and confirm the importance of input parameters on outputs, selected cases were simulated with CFD. As a result of all analyses, it was revealed that barrier usage is the most dominant input parameter on CG deviation followed by volume fraction, cutout hole diameter, cutout divergence, and finally, the number of cutout holes. This study identifies the dominant input parameters to control fuel sloshing, specifically CG deviation and retreat time in the fuel tank, and proposes baffle designs to promote robust flight stability. [ABSTRACT FROM AUTHOR]

The prevalence of elevated reinforced concrete tanks is widespread across Italian water distribution networks, particularly in flat or low-relief areas. Primarily constructed by the late 1970s, these tanks often suffer from outdated hydraulic efficiency, unable to cope with the increasing urban water demands. With rising construction costs, the economic advantage has shifted toward underground tanks, leading to the decommissioning of many elevated tanks. Despite being obsolete, elevated tanks from the 1960s and 1970s still stand in densely urbanized regions. However, demolishing them may prove less cost-effective than retrofitting to restore their original structural capacity. The widespread presence of these structures, coupled with their susceptibility to decay from weathering and poor maintenance, necessitates a comprehensive assessment of their resilience against gravitational and lateral forces, including seismic activity. Consequently, there is a pressing need to develop an analysis and verification methodology, particularly focused on seismic resilience, tailored to existing elevated tanks. These structures, distinct from conventional reinforced concrete frames, are primarily designed to withstand vertical forces, emphasizing the importance of optimizing material usage in their retrofitting efforts. [ABSTRACT FROM AUTHOR]

Shallow-water fluid sloshing in the Lagrangian Particle Path formulation, with the addition of an energy-extracting porous baffle, is simulated numerically using a symplectic numerical scheme which captures, in an essential way, the energy exchange. The fluid motion in a rectangular vessel is dynamically coupled to a surface-piercing porous baffle. The fluid transmission through the baffle is characterized by a nonlinear Darcy–Forchheimer model equation. The numerical scheme is symplectic, based on the implicit-midpoint rule, and thus is strategically designed to maintain the energy partition between the fluid and vessel throughout numerous time steps. Our results demonstrate the non-conservative nature of the system, with the porous baffle effectively dissipating energy from the overall system. Furthermore, we present findings that demonstrate the role of time-periodic variations in baffle porosity on energy dissipation. By manipulating the frequency and magnitude of this time-dependent variability, it is established that a greater amount of energy can be extracted from the system compared with the optimal fixed porosity baffle. These results shed new light on potential strategies for enhancing energy dissipation in such configurations. [ABSTRACT FROM AUTHOR]

This paper addresses the phenomenon of sloshing and the issues that arise during liquid handling at visual inspection stations. The pharmaceutical industry, recently put under pressure by the pandemic, has long adopted modular solutions consisting mainly of robotic islands. This work focuses on a visual inspection island for glass vials and ampules called VRU. This machine uses robotic arms to optimize the inspection process and enables automated control of a wide range of products using image recognition techniques and AI algorithms. However, the handling of containers in the presence of liquids requires special precautions to avoid the occurrence of bubbles inside the fluid that can prevent the cameras from correctly capturing any defects present. The banal solution involves a drastic reduction in the speeds and accelerations to which the liquids are subjected. However, using appropriate techniques makes it possible to achieve performance values similar to those obtainable when manipulating solid materials. The developed algorithms were tested using multibody simulations in the Mathworks Simscape environment and then validated using a six-axis Fanuc robot. In this study, however, the analysis conducted aimed to determine the correlations between trajectories, laws of motion, and sloshing in containers handled at high speed in industrial applications. In this study a multibody model was developed using a CFD analysis. The container consisted of a glass vial for pharmaceutical uses containing a liquid inside. The results obtained from the CFD analysis allowed us to calibrate the multibody model for the next phase of optimization of the laws of motion to be followed by the manipulator. [ABSTRACT FROM AUTHOR]

The current investigation delved into the seismic analysis, design intricacies, and assessment of the response of elevated steel containment tanks when supported by concentrically braced frames. The primary focus was placed on comprehending the behavior of the supporting structure, recognizing its heightened vulnerability to damage under horizontal excitation—insights gleaned from reconnaissance teams studying earthquake aftermaths worldwide. A specific case study unfolded featuring a steel concentrically braced frame as the supporting structure, aligning with prevalent industry norms. Throughout the entire process, spanning design phases, seismic vulnerability assessments, and response evaluations, special emphasis was placed on the internal fluid sloshing phenomena. This nuanced consideration plays a pivotal role in shaping the dynamic response of the system. The study introduces two distinct design methods: the first method aligns with relevant international codes, while the second method innovatively incorporates the compressive strength of the braces into its approach. To evaluate the dynamic response of the elevated tank, both linear and nonlinear advanced analyses were employed. The comparative analysis of various strategies underscores the impact of the chosen design methodology on the overall system response. This multifaceted exploration aims to contribute valuable insights to the seismic resilience and design optimization of elevated steel containment tanks, furthering the understanding of their performance under seismic forces. [ABSTRACT FROM AUTHOR]

Understanding violent sloshing is of practical concern to a wide range of applications as it may compromise safety in a number of engineering applications. The present study investigates violent sloshing in a 2D tank. In particular, the evolution and influence of an air pocket and the impact pressure on tank walls are numerically studied. Since the problem involves multi-phase flows, standard dam-break problem is used for validations. The liquid depth and amplitude of excitation are systematically varied to assess the impact pressures on walls and roof of the tank. Non-linear effects are captured qualitatively and the distribution of impact pressures on the tank walls is examined. The entrainment of an air pocket by a standing wave at the tank roof is delineated. The violent sloshing wave motion causes the formation of air pockets that arise for a range of forcing amplitudes and a variety of liquid depths. Gradual decay in the impact pressure due to the generation of these air pockets is significant on overall sloshing dynamics. The maximum peak pressure predicted on the tank roof is about 10 times the static pressure, which is also about twice the peak pressure obtained on the side wall. Furthermore, the distribution of average impact-pressure profiles on the tank walls and roof is presented for different loading conditions vis-á-vis global impact characteristics of sloshing wave motion. [ABSTRACT FROM AUTHOR]

This paper addresses the semi-analytical modeling and stability analysis of coupled slosh-tank dynamics within a multi-body system framework using the Homotopy Perturbation Method (HPM). The sloshing motion of the liquid inside the tank is represented using an equivalent pendulum model, which allows for a more accurate depiction of the dynamics involved. Nonlinear equations of motion are derived using the Lagrangian approach to account for lateral and longitudinal excitations, explicitly focusing on compressive oscillations. Our model investigates the influence of critical parameters, including viscous damping, amplitude, and excitation frequency. These parameters are examined at two specific points, one within and one outside the stability regions, to understand their effects on the overall system behavior. The study demonstrates that viscous damping is particularly significant in moving points from unstable to stable regions compared to other principal parameters. Simulations are conducted to visualize stability phenomena through stability diagrams, phase portraits, and time histories of sloshing amplitude. The results obtained using HPM are compared to those from the numerical Runge-Kutta method, validating the analytical approach. This comparison highlights the effectiveness of HPM in accurately capturing the dynamics and stability characteristics of coupled slosh-tank systems, offering valuable insights into the design and control of such systems. [ABSTRACT FROM AUTHOR]

This research aims to develop an efficient and accurate model for simulating tuned liquid dampers (TLDs) with sloped beds. The model, based on nonlinear shallow water equations, is enhanced by introducing new terms tailored to each specific case. It employs the central upwind method and Minmod limiter functions for flux and interface variable assessment, ensuring both high accuracy and reasonable computational cost. While acceleration, slope, and dissipation are treated as explicit sources, an implicit scheme is utilized for dispersion discretization to enhance the model's stability, resulting in matrix equations. Time discretization uses the fourth-order Runge–Kutta scheme for precision. The performance of the model has been evaluated using several test cases including dam-breaks on flat and inclined beds and run-up and run-down simulations over parabolic beds, which are relevant to sloshing in tanks with sloped beds. It accurately predicts phenomena such as asymmetric sloshing waves, especially in sloped beds, where pronounced waves occur. Dispersion and dissipation terms are crucial for capturing these effects and maintaining stable wave patterns. An initial perturbation method assesses the tank's natural period and numerical diffusion. Furthermore, the model integrates with a single-degree-of-freedom (SDOF) system to create a TLD model, demonstrating enhanced damping effects with sloped beds. [ABSTRACT FROM AUTHOR]

Reusable rockets must rely on well-designed Guidance, Navigation and Control (GNC) algorithms. Because they are tested and verified in closed-loop, high-fidelity simulators, emphasizing the strategy to achieve such advanced models is of paramount importance. A wide spectrum of complex dynamic behaviors and their cross-couplings must be captured to achieve sufficiently representative simulations, hence a better assessment of the GNC performance and robustness. This paper focuses on of the main aspects related to the physical (acausal) modeling of reusable rockets, and the integration of these models into a suitable simulation framework oriented towards GNC Validation and Verification (V&V). Firstly, the modeling challenges and the need for physical multibody models are explained. Then, the Vertical Landing Vehicles Library (VLVLib), a Modelica-based library for the physical modeling and simulation of reusable rocket dynamics, is introduced. The VLVLib is built on specific principles that enable quick adaptations to vehicle changes and the introduction of new features during the design process, thereby enhancing project efficiency and reducing costs. Throughout the paper, we explain how these features allow for the rapid development of complex vehicle simulation models by adjusting the selected dynamic effects or changing their fidelity levels. Since the GNC algorithms are normally tested in Simulink®, we show how simulation models with a desired fidelity level can be developed, embedded and simulated within the Simulink® environment. Secondly, this work details the modeling aspects of four relevant vehicle dynamics: propellant sloshing, Thrust Vector Control (TVC), landing legs deployment and touchdown. The CALLISTO reusable rocket is taken as study case: representative simulation results are shown and analyzed to highlight the impact of the higher-fidelity models in comparison with a rigid-body model assumption. [ABSTRACT FROM AUTHOR]

A coupled numerical calculation method combining smooth particle hydrodynamics (SPH) and the finite element method (FEM) was implemented to investigate the seismic response of horizontal storage tanks. A numerical model of a horizontal storage tank featuring a free liquid surface under seismic action was constructed using the SPH-FEM coupling method. The stored liquid was discretized using SPH particles, while the tank and supports were discretized using the FEM. The interaction between the stored liquid and the tank was simulated by using the meshless particle contact method. Then, the numerical simulation results were compared and analyzed against seismic simulation shaking table test data to validate the method. Subsequently, a series of numerical models, considering different liquid storage volumes and seismic effects, were constructed to obtain time history data of base shear and top center displacement, which revealed the seismic performance of horizontal storage tanks. Numerical simulation results and experimental data showed good agreement, with an error rate of less than 18.85%. And this conformity signifies the rationality of the SPH-FEM coupling method. The base shear and top center displacement values obtained by the coupled SPH-FEM method were only 53.3% to 69.1% of those calculated by the equivalent mass method employed in the current code. As the stored liquid volume increased, the seismic response of the horizontal storage tank exhibited a gradual upward trend, with the seismic response increasing from 73% to 388% for every 35% increase in stored liquid volume. The maximum von Mises stress of the tank and the supports remained below the steel yield strength during the earthquake. The coupled SPH-FEM method holds certain advantages in studying the seismic problems of tanks with complex structural forms, particularly due to the representation of the flow field distribution during earthquakes by involving reservoir fluid participation. [ABSTRACT FROM AUTHOR]

The damping efficiency of vertical porous baffles is investigated for a dynamically coupled fluid-vessel system. The system comprises of a two-dimensional vessel, with a rectangular cross-section, partially filled with fluid, undergoing rectilinear motions with porous baffles obstructing the fluid motion. The baffles pierce the surface of the fluid, thus the problem can be considered as separate fluid filled regions of the vessel, connected by infinitely thin porous baffles, at which transmission conditions based on Darcy's law are applied. The fluid is assumed to be inviscid, incompressible and irrotational such that the flow in each region is governed by a velocity potential. The application of Darcy's law at the baffles is significant as it makes the system non-conservative, and thus the resulting characteristic equation for the normal modes leads to damped modes coupled to the moving vessel. Numerical evaluations of the characteristic equation show that the lowest frequency mode typically has the smallest decay rate, and hence will persist longest in an experimental setup. The maximum decay rate of the lowest frequency mode occurs when the baffles split the vessel into identically sized regions. [ABSTRACT FROM AUTHOR]

Fluid behavior in microgravity is different from in ground gravity since surface tension, viscous force, and wetting are dominant in this condition. In propellant tank for artificial satellite and future on-orbit spacecraft, sloshing due to disturbance and settling behavior by change of acceleration have to be understood for design of propellant supply system and attitude control system. These fluid behaviors in microgravity condition are affected by a dynamic wetting significantly, therefore it is important to understand dynamic wetting which dominates fluid behavior. We observed transient fluid behaviors in cylindrical containers upon entering microgravity conditions created by drop tower facility, and effect of viscosity and diameter of container on fluid behaviors were investigated. CFD (Computational Fluid Dynamics) analyses were conducted and these results were compared with experimental results. Additionally, it was confirmed that numerical model considering dependence of contact line velocity in dynamic contact angle by empirical and theoretical methods provided more reasonable results. In addition, the sloshing behaviors inside the cylindrical containers were investigated under applied horizontal and axial accelerations using both microgravity experiments and CFD. As a result, it was found that under conditions of low excitation acceleration and high viscosity coefficient of the liquid, where the fluid movement is minimal, the experimental and numerical analysis results exhibit good agreement. [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]

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]

The main goal of this paper is to provide a Reduced Order Model (ROM) able to predict the liquid induced dissipation of the violent and vertical sloshing problem for a wide range of liquid viscosities, surface tensions and tank filling levels. For that purpose, the Delta Smoothed Particle Hydrodynamics (δ -SPH) formulation is used to build a database of simulation cases where the physical parameters of the liquid are varied. For each simulation case, a bouncing ball-based equivalent mechanical model is identified to emulate sloshing dynamics. Then, an interpolating hypersurface-based ROM is defined to establish a mapping between the considered physical parameters of the liquid and the identified ball models. The resulting hypersurface effectively estimates the bouncing ball design parameters while considering various types of liquids, producing results consistent with SPH test simulations. Additionally, it is observed that the estimated bouncing ball model not only matches the liquid induced dissipation but also follows the liquid center of mass and presents the same sloshing force and phase-shift trends when varying the tank filling level. These findings provide compelling evidence that the identified ROM is a practical tool for accurately predicting critical aspects of the vertical sloshing problem while requiring minimal computational resources. [ABSTRACT FROM AUTHOR]

The sloshing response is crucial to the design and operation of aquaculture vessels and affects the safety of the culture equipment and the efficiency of the culture operation. A 1/50 scaled model was utilized to investigate the coupled sloshing response characteristics of a novel aquaculture vessel in a wave basin. Two wave directions (beam and head wave) and two filling levels (81.5% and 47.4%) are taken into account. The time-domain and frequency-domain characteristics of the sloshing response under the linear regular wave and extreme operational sea state were investigated using regular wave tests and irregular wave tests, respectively. The sloshing mechanism in the aquaculture tanks is complicated, due to the coupling effect between external waves, ship motion, and internal sloshing. In linear regular waves, the wave frequency mode dominates the sloshing response, which is larger under beam wave conditions than under head wave conditions and larger under half load conditions than full load conditions. The irregular wave test results confirmed the regular wave test conclusions, but the sloshing response has stronger nonlinearity, higher natural modes appeared, and the amplitude of the higher natural modes is also relatively larger. [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]

Sloshing refers to a certain kind of fluid movement that changes as it progresses. It possesses properties that are both nonlinear and exceedingly unpredictable, and these properties affect the tank wall. This effect may lead to structural wear, which in turn can cause the tank to fail. Benzene and gasoil liquids are used to test the effect of sloshing liquid and accompanying pressure on the wall tank caused by the baffles in partially full fluid tanks. To attain this, modeling of the interaction between fluid and structure is justified using the finite element analysis while the ANSYS Fluent is used to do the simulation. Specifically, the analysis enables us to anticipate the pressure that is being exerted on the shield, the influence of sloshing on the grounding point forces, and the size of the sloshing waves. The pressure distribution over time indicates a reduction of pressure on the tank wall as a result of utilising a vertical baffle if compared to the case of a tank wall without a baffle. The usage of vertical shields allows for around 20% of the greatest contact energy to be deflected, which is attributed to the potential of generating turbulence and vortices by the baffle. [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]

The moving pseudo-boundary method of fundamental solutions (MFS) was employed to solve the Laplace equation, which describes the potential flow in a two-dimensional (2D) numerical wave tank. The MFS is known for its ease of programming and the advantage of its high precision. The solution of the boundary value can be expressed by a linear combination of the fundamental solutions. The major issue with such an implementation is the optimal distribution of source nodes in the pseudo-boundary. Traditionally, the positions of the source nodes are assumed to be fixed to keep the set of equations closed. However, in the moving boundary problem, the distribution of source nodes may influence the stability of numerical calculations. Moreover, MFS is unstable in time iterations. Hence, it is necessary to constantly revise the weighting coefficients of fundamental solutions. In this study, the source nodes were free, and their locations were determined by solving a nonlinear least-squares problem using the Levenberg–Marquardt algorithm. To solve the above least-squares problem, the MATLAB© routine lsqnonlin was adopted. Additionally, the weighting coefficients of fundamental solutions were solved as a nonlinear least-squares problem using the aforementioned method. The numerical results indicated that the numerical simulation method adopted in this paper is accurate and reliable in solving the problem of 2D tank sloshing. The main contribution of this study is to expand the application of the MFS in engineering by integrating it with the optimal configuration problem of pseudo-boundaries to solve practical engineering problems. [ABSTRACT FROM AUTHOR]

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Purpose: In this study, a hybrid vibration-based energy harvester is proposed which utilizes electromagnetic and piezoelectric transduction mechanisms. Methods: The paper is divided into three parts: experimental investigation, numerical modeling and statistical analysis. In the experimental part, the system is prepared by floating a magnet inside a coiled fluid container. Then, the container is subjected to vibrations and voltage measurement is performed. Highest values for measured data in the experiments are 740 mV and 58 μW for peak-to-peak voltage and electrical power, respectively. In the second part, numerical modeling is used to investigate the effect of various parameters on the energy harvesting performance as well as to its design, analysis and prediction. Effective parameters are categorized as dimensionless numbers and simulations are designed using the response surface methodology (RSM) approach based on the central composite design (CCD) method. Results and Conclusions: The results show that there are many qualitative similarities between numerical graphs and experimental data and a preliminary estimate of the probable energy harvesting can be obtained from the variations of the interface parameters. Finally, the effect of considered parameters is statistically investigated using analysis of variance (ANOVA) method. The highest contribution percentage of input parameters on the numerical results are calculated which is related to the top to bottom side length ratio of the container and its amplitude of oscillations. [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]

The LNG cargo containment system used in membrane-type LNG cargo tanks must have sufficient dynamic strength to withstand the impact of sloshing loads. However, performing direct dynamic nonlinear transient finite element assessments against design sloshing impact loads with different design specifications can be complicated and time-consuming. To address this, it is effective to use linear superposition methods, such as the triangular impulse response function (TIRF) method, to conduct dynamic transient FE assessments of LNG cargo containment systems. However, as LNG cargo containment systems have a high level of nonlinearities in terms of geometry, material, and boundary effects, it is necessary to evaluate the applicability of the TIRF method in advance. This study investigates the dynamic responses of an LNG cargo containment system using the TIRF method and compares the ultimate value of the structural responses and impulses with that obtained using direct dynamic nonlinear transient assessments. Based on a comparison of a series of FE analyses, the study proposes a design for the partial safety factors for calculating the ultimate bending and shear capacities of an LNG cargo containment system, taking into consideration the dynamic impact of sloshing loads using the TIRF method. Finally, the ultimate shear and bending capacities are calculated using the proposed method and compared with those obtained through direct dynamic nonlinear transient assessments. The results show that the proposed method provides conservative estimates against direct nonlinear finite element simulations, with a difference of around 10% for the mean minus two standard deviations. This approach can be practically applied for early basic design purposes in the shipbuilding industry. [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]

To clarify distribution characteristics of impact pressure induced by sloshing along the rectangular tank wall and predict the vertical position where the maximum pressure appears, this paper uses VOF method and dynamic mesh technique to simulate the sloshing in the rectangular tank and analyze the sloshing pressure under different conditions. The results show that the vertical position of the maximum sloshing pressure decreases with the increase of the impact strength when liquid does not impact the roof of the tank. The vertical position of the maximum sloshing pressure decreases with the increase of the excitation amplitude. The relationship between the vertical position of the maximum sloshing pressure and the excitation frequency presents parabola-like characteristics and the parabola opens up, which means the vertical position has the minimum value with the change of the excitation frequency, and the minimum of the vertical position occurs when the liquid in the tank near the resonance state. It also shows that the maximum sloshing pressure does not always appear at the static free surface corresponding to different filling levels. Instead, it is distributed regionally as the filling level changes. [ABSTRACT FROM AUTHOR]

An efficient method to predict extreme pressures considering the sloshing in a rectangular tank subjected to in-plane irregular rotational motions is proposed. First Order Reliability Method (FORM) is applied to evaluate the probability distribution of pressure, while the open-source Smoothed-Particle Hydrodynamics (SPH) code DualSPHysics is used for obtaining time-domain pressures. To attain an efficient extreme value prediction, a simplified surrogate model is formulated so that the SPH results are represented with fast computations. An efficient extreme value prediction is achieved without directly using SPH to the series calculations with various stochastic variables during FORM. FORM results are validated by comparing the reliability index with the Monte Carlo Simulation. Finally, the difference in the sloshing-induced impact pressures evaluated by the two-dimensional and three-dimensional SPH under the most probable wave episodes obtained by FORM is presented, and then the applicability of the present surrogate model to the three-dimensional SPH is demonstrated. [ABSTRACT FROM AUTHOR]

Copyright of Acta Mechanica Sinica is the property of Springer Nature and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Liquid storage, particularly oil and petrochemical products which are considered hazardous liquid, are an important part of the oil industry. Thin-walled vertical cylindrical steel storage tanks are widely used in recent years. Due to high sensitivity of these structures in an earthquake and other external excitations may lead to catastrophic consequences. For instance, huge economic losses, environmental damages, and casualities, many studies have been done about these structures. past studies showed that liquid storage tanks, equipped with a floating roof, are potentially vulnerable while subjected to seismic loads and earthquake has been considered as one of the most destructive natural hazards. The reason is that such tanks are made of two separated parts (shell and roof) which each may have its own responses; sometimes causing resonance phenomenon and so that, roof movements, rooffluid interaction, roof-shell interaction, and also the way they are attached should still be investigated. Experimental tests of floating roof 's vertical fluctuation was performed in a full-scale reservoir tank and assessing of the results demonstrated that presence of a seal between floating roof and shell plate can significantly increase damping ratio in liquid sloshing and also suppress the roofs vertical displacements. In other words, seal can control a floating roof and make it stop moving vertically over few cycles. [ABSTRACT FROM AUTHOR]

This study examines the effect of the number of perforated baffles in sloshing phenomenon in a partially filled tank. The natural frequencies in one-, two- and no-baffle cases are experimentally obtained; change in natural frequencies and reduction in sloshing impacts due to baffles are reported. It is observed that adding the second baffle has a minor effect in damping the sloshing loads at non-resonance frequencies in comparison to ones obtained in one-baffle sloshing tests. Although the natural frequency is significantly increased and pressure distribution profile is altered at higher oscillation frequencies in two-baffle case, the significant reduction in peak pressure values is observed at the frequencies near the natural frequency in one-baffle case. The results indicate that the number of the baffles should be optimised considering the natural frequency of the carrier and external excitation frequencies for the purpose of weight minimisation, fast loading and unloading of the tanks. [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]

Copyright of Media Mesin: Majalah Teknik Mesin is the property of Media Mesin: Majalah Teknik Mesin and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

As part of the Sloshing Wing Dynamics H2020 EU project, an experimental campaign was conducted to study slosh-induced damping in a vertically excited tank filled with liquid water or oil and air. In this work, we simulate these experiments using two numerical approaches. First, a single-phase, weakly compressible liquid model is used, and the gas flow (air) is not modeled. For this approach, a proven Smoothed Particle Hydrodynamics (SPH) model is used. In the second approach, both phases are simulated with an incompressible liquid and weakly compressible gas model via a Finite Volume Method (FVM) using Volume-of-Fluid (VOF) to track the liquid phase. In both approaches, the energy distribution of the flow is calculated over time in two- and three-dimensional simulations. It is found that there is reasonable agreement on the energy dissipation evolution between the methods. Both approaches show converging results in 2D simulations, although the SPH simulations seem to have a faster convergence rate. In general, the SPH results tend to overpredict the total dissipation compared to the experiment, while the finite volume 2D results underpredict it. Time histories of the center of mass positions are also compared. The SPH results show a much larger vertical center of mass motion compared to the FVM results, which is more pronounced for the high Reynolds number (water) case, probably linked to the absence of the air phase. On the other hand, the limited center of mass motion of the FVM could be linked to the need for higher spatial resolutions in order to resolve the complex gas–liquid interactions, particularly in 3D. [ABSTRACT FROM AUTHOR]

This research studies how the angle and dimensions of a single baffle affect the dynamics of a fluid in a closed rectangular tank under an accelerated harmonic vibration in resonance. A half-filled non-deformable rectangular tank with a single centered submerged baffle has been simulated using ANSYS® FLUENT. The study aims to characterize the effect of changing the baffle's angle; hence, 10 simulations have been performed: without a baffle, 90°, 30°, 60°, 120° and 150°, either maintaining the baffle's length or the projected height constant. The computational fluid dynamics (CFD) method using volume of fluid (VOF) and large eddy simulation (LES) are used to predict the movement of the fluid in two dimensions, which have been benchmarked against experimental data with excellent agreement. The motion is sinusoidal in the +X direction, with a frequency of oscillation equal to its first vibration mode. The parameters studied have been the free surface elevation, values at three different points and maximum; the center of gravity's position, velocity, and acceleration; and the forces against the tank's walls. It has been found that the 90° angle has the most significant damping effect, stabilizing the free-surface elevation, reducing the center of gravity dispersion, and leveling the impacting forces. Smaller angles also tame the sloshing and stabilize it. [ABSTRACT FROM AUTHOR]

Under variable speed condition, oil in a fuel tank is shaken violently, thereby causing damage to the fuel tank structure and supply interruption, affecting the safe driving of the vehicle. A structural design scheme of a fuel tank with cross-linked baffle is proposed. Oil sloshing in the fuel tank under braking conditions is numerically simulated using a method verified by experiments. The characteristics of cross-linkage baffled fuel tanks to inhibit oil sloshing are analysed. The results show that the baffles can be linked when stiffeners are installed between baffles in the fuel tank. Applying the force opposite to the oil impact pressure improves the rigidity of the baffle and enables a reduction in fatigue damage. The cross-linked baffled has little influence on the baffle wall pressure but has a certain impact on the shape of oil sloshing. With the increase of braking acceleration, the jet velocity of the oil passing through the baffle pores increases, and the nonlinear phenomenon caused by the jet hitting the liquid surface is further aggravated. With the rise of the fuel tank filling rate, the jet velocity of the oil passing through the baffle pores decreases, and the intensity of sloshing is reduced. The vortex generated near the cross-linked baffle changes the flow field structure, reduces the oil climbing speed, and ultimately restrains sloshing. [ABSTRACT FROM AUTHOR]

This paper presents the result obtained from a series of experiments conducted on different scaled rectangular tanks mounted on shake table, to study the scale effects of sloshing with sway excited motion. Three different tanks of model scales of 1:86, 1:57 and 1:43 are considered for present study. The tests are carried out for the aspect ratio (hs/l, where hs liquid depth and l is the length of the tank) of 0.1625, 0.325, and 0.4875 which represents 25%, 50% and 75% of liquid fill levels, respectively. The sloshing oscillations occur in the longitudinal axis when subjected to sway excitations. Sloshing forces and sloshing oscillation time histories are measured using load cells and wave probes, respectively. The effect of excitation amplitudes and excitation frequencies on sloshing oscillations and sloshing force are presented herein. It is found that violent sloshing is experienced for 50% filled condition irrespective of scaled tanks, excitation amplitudes and excitation frequencies. The sloshing force is maximum in 1:43 scaled tank than other scaled sloshing tanks irrespective of the excitation frequency and amplitude for 50% fill level. Based on the experimental observations and analysis of results, it is concluded that proportionate volume of water and tank size decides the severity of sloshing in the partially filled moving tanks. [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]

The purpose of this study is to improve the gas–liquid separation performance of an oil tank and to establish a design method to enable gas–liquid separation only in an oil tank. Since it is difficult for conventional oil tanks to completely remove bubbles remaining in the hydraulic oil, it is essential to introduce a technology to actively separate and remove bubbles from the oil. Therefore, the bubble removal performance was improved even under the condition of added lateral acceleration by appropriately generating a swirl flow. First, an acrylic model of an oil tank was used to verify the accuracy by performing numerical analysis using various turbulence models. Then, the parameters of the bubble remover, such as the size of the oil tank, were studied. In addition, the bubble removal performance under the condition of added lateral acceleration was examined. [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]

This paper introduces an outlier analysis which can improve the convergence of the statistical analysis results of sloshing model test data. The paper classify possible outliers in the sloshing model test into three categories and present a treatment method for each outlier. The developed outlier analysis is adapted to the model test results for the cargo of the liquefied-natural-gas (LNG) carrier in operation. The results of the present new method are compared with those of the conventional procedure, particularly focusing on long-term sloshing prediction. Through this study, the effectiveness of the present method is observed, and it is found that the present method provides is robust and reliable results in the application of experimental data for load prediction. [ABSTRACT FROM AUTHOR]

Base shear and sloshing response control in ground-supported circular cylindrical liquid storage tank is achieved by oblate spheroid base isolation (OSBI) system used along with floating surface diaphragm on the contained liquid. The new base isolation system, OSBI proposed herein is based on rolling-friction mechanism in ellipsoidal-shaped isolators in both the horizontal axes. The surface diaphragm is proposed to float on the free liquid surface to control the sloshing amplitude. The tank is analyzed using the coupled acoustic-structural (CAS) approach in finite element method (FEM). In order to have conformity of the present FE model, the FEM results are compared with the mechanical lumped-mass model of the tank (without surface diaphragm). The seismic response is investigated for the tank subjected to harmonic and real-earthquake excitations. The parameters considered for the analysis are the aspect ratio of the tank, eccentricity of the isolator, and thickness of the diaphragm. The seismic response quantities evaluated are base shear, sloshing displacement, and impulsive hydrodynamic pressure in the tank. Further, to study the effectiveness of the OSBI, the seismic responses of the tank subjected tri-directional components are compared with the two horizontal bi-directional components of the earthquakes. Also, the sloshing displacement with and without surface diaphragm in the non-isolated and base-isolated tanks are compared. From the results, it is observed that the OSBI system is efficient in mitigating the seismic responses in the tanks and the surface diaphragm is efficient in controlling the sloshing displacement. The superior performance of the proposed isolator depends on the design parameters, namely, eccentricity, and coefficient of rolling friction selected. The effectiveness of the surface diaphragm depends on the choice of material and thickness adopted. [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]