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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 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 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]

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.

This research investigates liquid sloshing in a 3D rigid rectangular tank. The impact of rigid baffle on sloshing frequencies has been studied. The mathematical modal has been developed using potential theory. The boundary value problem has an analytical solution in terms of velocity potential with undetermined frequency. We get a system of homogeneous algebraic equations using boundary and free surface conditions. The frequencies are calculated using the non-trivial solution condition. Frequencies of baffled tank are computed for various filling levels. The effects of filling level on frequencies are identified. ANSYS software is used to report the liquid domain and rigid baffle mode forms.

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]

We numerically investigate the effect on sloshing in microgravity of systems with passive, moving baffles whose motion is restricted by linear springs. The liquid is assumed to have physical properties similar to those of 5 cSt silicone oil while the baffle is made of aluminium. Two kinds of numerical models are developed depending on whether the allowed baffle motion is translational or rotational. Simulations show that moving baffles significantly improve sloshing mitigation compared to fixed baffles, with decreases of up to 48% in the decay time and 23% in the fluid kinetic energy following excitation by a certain pulse-like acceleration. In all configurations considered, there exists an optimal spring stiffness that minimises the kinetic energy or decay time. Frequency analysis reveals two peaks in the range of 0.1–2 Hz whose amplitudes vary as a function of spring stiffness, analogous to the behaviour of Tuned Mass Dampers (TMDs). The effectiveness of the moving baffle system is then assessed using a real microgravity perturbation measured during a reboosting manoeuvre of the International Space Station (ISS) and a significant reduction in decay time relative to the fixed baffle case is found: to 1.3 s from 4 s. • Moving baffles are investigated for sloshing reduction in microgravity. • Two configurations are analysed: allowing translational or rotational baffle motion. • Optimum spring stiffness minimises decay time and kinetic energy of the fluid system. • Microgravity perturbations are more effectively mitigated compared to fixed baffles. • A real microgravity scenario is tested with an ISS reboosting manoeuvre acceleration. [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]

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′.

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.

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.

The control of the evaporation rate is essential to the long-distance transportation of liquid hydrogen (LH 2). This paper conducts a numerical investigation of the thermodynamic characteristics in tanks with baffles under LH 2 sloshing conditions by establishing a computational fluid dynamics (CFD) model. The pressurization rate and vapor-liquid interface sloshing behavior predicted by the numerical model is validated against experimental data. The effects of baffles, amplitude, frequency, and storage pressure on thermodynamic characteristics such as temperature, pressurization rate, and evaporation rate of the LH 2 tank under sinusoidal sloshing are analyzed in detail. The simulation results suggest that adding baffles can effectively suppress the pressure fluctuation of LH 2 under sloshing conditions, but baffles as a "thermal bridge" accelerate the pressurization rate in the tank. Adding baffles during smooth transportation accelerates the pressurization rate. The baffles gradually demonstrate the effect of suppressing the pressurization rate as the acceleration amplitude increases. Assuming that the LH 2 evaporation rate is stable for a certain value, the daily evaporation rates in the LH 2 tank account for 2.59 % and 5.13 % when the maximum acceleration is 5.92 m/s2 and 9.87 m/s2, respectively, which contradicts the long-term storage goal of LH 2. The slower the sloshing frequency, the higher the maximum liquid phase level in the tank, and the faster the evaporation rate. The sloshing frequency has little effect on the LH 2 pressurization and evaporation rates compared to the amplitude. The growth of pressure decreases from 139.9 Pa to 85.62 Pa for a period of 15 s when the storage pressure in the tank increases from 0.1 MPa to 0.6 MPa. This study provides guidlines for the in-depth investigation of the thermodynamic behavior in LH 2 tanks during transportation. [Display omitted] • Thermodynamic analysis of liquid hydrogen tanks during sinusoidal sloshing. • LH 2 evaporation correlates positively with amplitude and negatively with frequency. • Increasing the storage pressure slows down the evaporation rate. • Baffles help reduce pressure fluctuation magnitude but increase evaporation. • Effects of Baffles on evaporation rate become insignificant for severe sloshing. [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]

AbstractThe effect of horizontal wave baffles on slosh reduction of rectangular tanks under combined surge and pitch excitation is investigated in this work. Two-dimensional numerical modeling of a rectangular tank is performed using the Volume of Fluid (VoF) technique. The validation studies are performed, and the results agree with the data available in the literature. This study also considers the influence of baffle characteristics on sloshing reduction, such as wave baffle amplitude and the number of wave baffle cycles. The cosine baffles with negative amplitude and increased baffle amplitude performed better than others. [ABSTRACT FROM AUTHOR]

Among various types of wave energy converters, the oscillating water column (OWC) has attracted significant research attention. In this paper, a 1:10 scale OWC with dimensions of 100×100×160 cm, variable inlet height and draft was numerically studied. Based on the tests conducted, it was found that the wave amplitude in the range of Caspian Sea waves decreased with the increase of wave frequency, to the extent that at the sloshing frequency, the system efficiency dropped significantly. To solve this problem, changes in the geometry of the device were studied, and numerical simulations were performed at the highest frequency using OpenFOAM software. Using Reynolds-averaged Navier-Stokes (RANS) equations, numerical simulations were performed in 3D, twophase, and turbulent flow conditions. Changing the geometry was initially investigated by adjusting the height of the OWC inlet duct, and then by adding an inlet at the different angles of 0, 20, and 40 degrees. The results showed that by increasing the height of the inlet by 10 cm while keeping the water depth and wave conditions constant, the maximum output power of the system increased by 54%. However, after the optimization of the inlet duct, it was found that the best angle for an inlet duct is 30°, compared to the case without an inlet, which increased the maximum output power by up to 13% and slightly reduced the sloshing by more than 50%. [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]

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]

In the automotive industry, the fuel tank is an essential component of the vehicle. It is; designed as an integral part of the fuel system to transport the fuel and deliver it to the engine via the fuel filter and fuel pump. In Ethiopia, it is observed that due to the smaller fuel tank of three-wheeled vehicles, more frequent visits to fuel stations result in a lot of time being wasted waiting in long queues at fuel stations. In addition, the current location of the fuel tank causes some stability problems. Subsequently, the method, location, installation techniques and stability analysis of the three-wheeled vehicle are carried out. This study includes a new design of fuel tanks for three-wheeled vehicles in which the capacity is doubled and the rollover stability; of the vehicle is maintained. The SOLIDWORKS software and the CFD software ANSYS FLUENT for the sloshing analysis were used for the modeling of this work. The CFD results of the comparative sloshing analysis of partially filled (50% level) fuel tanks with and without baffles are performed; and conclusions are drawn. It is concluded that a baffle plate for the fuel tank offers the greatest advantage in reducing the effects of sloshing. The newly developed part is mounted on the underside of the passenger seat. A bottom-mounted fuel tank optimizes the vehicle's center of gravity, as the height of the vehicle's center of gravity is lowered by 30 mm. This increases the rollover safety of the vehicle. According to the analysis, the mileage of the filled existing and new tanks is 136 km and 272 km respectively. To refuel once, the driver waits an average of 5 h and works about two days for the existing tank and four days for the new tank.

Among various types of wave energy converters, the oscillating water column (OWC) has attracted significant research attention. In this paper, a 1:10 scale OWC with dimensions of 100×100×160 cm, variable inlet height and draft was numerically studied. Based on the tests conducted, it was found that the wave amplitude in the range of Caspian Sea waves decreased with the increase of wave frequency, to the extent that at the sloshing frequency, the system efficiency dropped significantly. To solve this problem, changes in the geometry of the device were studied, and numerical simulations were performed at the highest frequency using OpenFOAM software. Using Reynolds-averaged Navier-Stokes (RANS) equations, numerical simulations were performed in 3D, two-phase, and turbulent flow conditions. Changing the geometry was initially investigated by adjusting the height of the OWC inlet duct, and then by adding an inlet at the different angles of 0, 20, and 40 degrees. The results showed that by increasing the height of the inlet by 10 cm while keeping the water depth and wave conditions constant, the maximum output power of the system increased by 54%. However, after the optimization of the inlet duct, it was found that the best angle for an inlet duct is 30°, compared to the case without an inlet, which increased the maximum output power by up to 13% and slightly reduced the sloshing by more than 50%.

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.

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.

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.