Recent advances in liquid sloshing dynamics (original) (raw)
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Study of liquid sloshing: numerical and experimental approach
Computational Mechanics, 2011
In this paper, sloshing phenomenon in a rectangular tank under a sway excitation is studied numerically and experimentally. Although considerable advances have occurred in the development of numerical and experimental techniques for studying liquid sloshing, discrepancies exist between these techniques, particularly in predicting time history of impact pressure. The aim of this paper is to study the sloshing phenomenon experimentally and numerically using the Smoothed Particle Hydrodynamics method. The algorithm is enhanced for accurately calculating impact load in sloshing flow. Experiments were conducted on a 1:30 scaled two-dimensional tank, undergoing translational motion along its longitudinal axis. Two different sloshing flows corresponding to the ratio of exciting frequency to natural frequency were studied. The numerical and experimental results are compared for both global and local parameters and show very good agreement.
Experimental and numerical study of liquid sloshing in a rectangular tank with three fluids
Sloshing experiments are reported with a rectangu- lar tank filled with three fluids of different densities. The tank undergoes harmonic and multichromatic forced motions, in sway then roll. The positions of the interfaces at the tank end are video-tracked and RAOs are extracted through image processing and Fourier/spectral analysis. An analytical model, based on linearized potential flow theory, is described and its predictions are compared with experimental RAOs, with good agreement. Comparisons are also presented with results from a fully nonlinear CFD code with VOF tracking of the interfaces. This investigation is relevant for the design of wash-tanks installed aboard FPSOs.
Journal of Naval Architecture and Marine Engineering, 2013
In order to explore the physics implicated with the sloshing phenomenon subjected to independent regular sway, heave and roll excitations of the liquid tank system, theoretical studies are carried out. Four liquid fill levels with static liquid depth, hs, to the length, l of aspect ratio (hs/l) 0.163, 0.325, 0.488 and 0.585, are considered. The energy spectra of sloshing oscillation, their qualitative assessment and the harmonics present in the sloshing oscillation are studied. Frequency Response amplitude has also been presented. The study reveals that sway excites a particular mode of sloshing (primary harmonic) by fulfilling the resonance conditions and also excites secondary modes. However, the roll motion excites the first mode of sloshing irrespective of the excitation frequencies. The heave motion excites the particular mode which is assumed as an initial perturbation.DOI: http://dx.doi.org/10.3329/jname.v10i2.16215
Nonlinear Sloshing in Fixed and Vertically Excited Containers
5th International Symposium on Fluid Structure International, Aeroeslasticity, and Flow Induced Vibration and Noise, 2002
ABSTRACT Nonlinear effects of standing wave motions in fixed and vertically excited tanks are numerically investigated. The present fully nonlinear model analyses two-dimensional waves in stable and unstable regions of the free-surface flow. Numerical solutions of the governing nonlinear potential flow equations are obtained using a finite-difference time-stepping scheme on adaptively mapped grids. A σ-transformation in the vertical direction that stretches directly between the free-surface and bed boundary is applied to map the moving free surface physical domain onto a fixed computational domain. A horizontal linear mapping is also applied, so that the resulting computational domain is rectangular, and consists of unit square cells. The small-amplitude free-surface predictions in the fixed and vertically excited tanks compare well with 2nd order small perturbation theory. For stable steep waves in the vertically excited tank, the free-surface exhibits nonlinear behaviour. Parametric resonance is evident in the instability zones, as the amplitudes grow exponentially, even for small forcing amplitudes. For steep initial amplitudes the predictions differ considerably from the small perturbation theory solution, demonstrating the importance of nonlinear effects. The present numerical model provides a simple way of simulating steep non-breaking waves. It is computationally quick and accurate, and there is no need for free surface smoothing because of the σ-transformation.
A fully nonlinear model for sloshing in a rotating container
In this paper a theoretical and experimental analysis of sloshing in 2D and 3D free-surface con gurations is performed. In particular, the case of a tank rotating around a horizontal axis has been considered. The uid is assumed to be incompressible and inviscid. A fully nonlinear mathematical model is de ned by applying the variational method to the sloshing. The damping of gravity waves has been accounted by introducing a suitable dissipation function from which generalized dissipative forces are derived. A modal decomposition is then adopted for the unknowns and a dynamical system is derived to describe the evolution of the physical system. An experimental technique has been applied to select the leading modes, whose evolution characterizes the physical process, i.e. captures the most of the kinetic energy of the process. A very good agreement between experimental and numerical results con rms the validity of the methodological approach followed.
Water Sloshing in Rectangular Tanks - An Experimental Investigation & Numerical Simulation
2000
This paper presents the steps involved in designing a test rig to study water sloshing phenomenon in a 560 x 160 x 185 mm PVC rectangular container subjected to sudden (impulsive) impact. The design encompasses the construction of the testing facility and the development of a proper data acquisition system capable of capturing the behavior of pre- and post impact
Journal of Fluids and Structures, 2020
In liquid storage tanks, rotary sloshing occurs when the frequency of the lateral harmonic load is near the lowest frequency of the tank-liquid system. Rotary sloshing is a type of sloshing that modifies the tank response, which may cause instabilities of the tank wall. However, the consequences of rotary sloshing for the development of strain in the tank wall have not been elucidated. This paper presents an experimental determination of the effects of rotary sloshing on the development of strain and acceleration at various locations of a storage tank. A low-density-polyethylene tank containing water was tested using a shake table. Nine excitations with frequencies near the first free-vibration frequency of the tank-water system were employed. To suppress rotary sloshing, a highdensity foam floating lid was utilised as a barrier. Results reveal rotary sloshing boosts not only the development of both hoop and axial strain but also the acceleration in the horizontal direction perpendicular to the excitation. The lid reduced the maximum hoop and axial strain by 500% and 400%, respectively compared to that when rotary sloshing occurs. Moreover, the lid suppressed the nonplanar sloshing by erasing the first three free-vibration frequencies of the tank-water system without the lid.
Analytical Study of Transient Coupling between Vessel Motion and Liquid Sloshing in Multiple Tanks
Journal of Engineering Mechanics, 2016
The transient coupling between the vessel motion and liquid sloshing in multiple tanks is investigated. External disturbance factors (e.g., spring constraint or force field) that might affect the oscillation characters of the coupling system are not involved so that the vessel motion is only excited by the liquid sloshing in tanks. The analytical solution for this coupling problem has been derived based on the potential flow theory, which converts the problem to a linear system of ordinary differential equations. The approach to determine natural frequencies of the coupling system is also given. The vessel with one or more rectangular tanks is considered for cases studies. Effects of factors, such as vessel mass, number of tanks, tank configuration and free-surface deformation on the vessel motion, liquid sloshing, and mechanical-energy components of the system are studied systematically.
Effects of baffles geometry on sloshing dynamics of a viscous liquid tank
Scientific Research and Essays, 2013
Baffles are used effectively to reduce the sloshing response of liquid in the liquid storage containers. In this paper, a brief equivalent method is proposed to model the influence of different baffle geometrical effects on liquid sloshing. It has been showed that the natural frequencies and the dynamic response of the liquid in the container are drastically changed if the free liquid surface in a cylindrical container is being covered with structural parts. The advantages of a partly covered free surface plane lies in the shifting of the natural propellant frequencies above and away from the control frequency of a space vehicle, and in the decrease of the sloshing masses participating in the dynamic motion of the system. The fundamental natural frequency of a viscous and incompressible liquid has been determined for different geometrical shape and width of an annular ring baffle attached to the tank wall. The response to translational and pitching excitation has also been evaluated and showed the shifting of the resonance margins to higher values. Simulation results showed the effectiveness of this procedure. The presented approach may be applied to the various arbitrary coverage of free liquid surface and different geometry of container.