Coupled vibrations of a partially fluid-filled cylindrical container with an internal body including the effect of free surface waves (original) (raw)
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Coupled vibration of a partially fluid-filled cylindrical container with a cylindrical internal body
Journal of Fluids and Structures, 2009
In the present paper a method is proposed to investigate the effects of a rigid internal body on the coupled vibration of a partially fluid-filled cylindrical container. The internal body is a thin-walled and open-ended cylindrical shell. The internal body is concentrically and partially submerged inside a container. The radial and axial distances between the internal body and the container are filled with fluid. Along the contact surface between the container and the fluid, the compatibility requirement for the fluid-structure interactions is applied and the Rayleigh-Ritz method is used to calculate the natural frequencies and modes of a partially fluid-filled cylindrical container. The fluid domain is continuous, simply connected, and non-convex. The fluid is assumed to be incompressible and inviscid. The velocity potential for fluid motion is formulated in terms of eigenfunction expansions for two distinct fluid regions. The resulting equations are solved by using the Galerkin method. The results from the proposed method are in good agreement with experimental and numerical solutions available in the literature for the partially water-filled cylindrical container without internal body. A finite element analysis is also used to check the validity of the present method for the partially water-filled cylindrical container with internal body. The effects of the fluid level, internal body radius, and internal body length on the natural frequencies of the coupled system are also investigated. r
In this paper we develop a three-dimensional, fully coupled, partitionedbased fluid-structure interaction (FSI) model for liquid sloshing analysis in partially filled containers. Different tank geometries are considered in the present study focusing on both the rigid and flexible baffles and their influence on slosh loads at the tank walls. For the purpose of validation, we develop a stand-alone CFD model and compare the results with the previously existing numerical model and experimental data from the literature. Once such a validation is complete, we incorporate a rigid baffle like obstruction to study the effect of the baffle on sloshing using the stand alone CFD model. The numerical simulations predict that the influence of baffle like obstructions can help in mitigating the tank resonance.
Journal of Sound and Vibration, 1997
Recently published studies on natural vibration of vertical thin-walled cylindrical tanks containing liquid or cylindrical shells in contact with a liquid layer in an inner coaxial annular region [2] dealt with the finite element (FE) modelling of spectral and modal characteristics of such systems. The developed FE models, where only the inviscid fluid was considered, were experimentally verified by means of modal analysis and holographic techniques. The agreement between the computed and measured natural frequencies and mode shapes of vibration was very good in both the cases studied [1, 2], however, no damping properties were modelled by the FE method.
Low Frequency Sloshing Analysis of Cylindrical Containers with Flat and Conical Baffles
International Journal of Applied Mechanics and Engineering, 2017
This paper presents an analysis of low-frequency liquid vibrations in rigid partially filled containers with baffles. The liquid is supposed to be an ideal and incompressible one and its flow is irrotational. A compound shell of revolution is considered as the container model. For evaluating the velocity potential the system of singular boundary integral equations has been obtained. The single-domain and multi-domain reduced boundary element methods have been used for its numerical solution. The numerical simulation is performed to validate the proposed method and to estimate the sloshing frequencies and modes of fluid-filled cylindrical shells with baffles in the forms of circular plates and truncated cones. Both axisymmetric and non-axisymmetric modes of liquid vibrations in baffled and un-baffled tanks have been considered. The proposed method makes it possible to determine a suitable place with a proper height for installing baffles in tanks by using the numerical experiment.
European Journal of Mechanics-A/Solids, 2010
An analytical method is developed to consider the free vibration of an elastic bottom plate of a partially fluid-filled cylindrical rigid container with an internal body. The internal body is a rigid cylindrical block that is concentrically and partially submerged inside the container. The developed method captured the analytical features of the velocity potential in a non-convex, continuous, and simply connected fluid domain including the interaction between the fluid and the structure. The interaction between the fluid and the bottom plate is included. The Galerkin method is used for matching the velocity potentials appropriate to two distinct fluid regions across the common horizontal boundary (artificial horizontal boundary). Then, the Rayleigh–Ritz method is also used to calculate the natural frequencies and modes of the bottom plate of the container. The results obtained for the problem without internal body are in close agreement with both experimental and numerical results a...
International Journal of Applied Mechanics and Engineering, 2020
The paper is devoted to issues of estimating free surface elevations in rigid cylindrical fluid-filled tanks under external loadings. The possibility of baffles installation is provided. The liquid vibrations caused by lateral and longitudinal harmonic loadings are under consideration. Free, forced and parametrical vibrations are examined. Modes of the free liquid vibrations are considered as basic functions for the analysis of forced and parametric vibrations. The modes of the free liquid vibrations in baffled and un-baffled cylindrical tanks are received by using single-domain and multi-domain boundary element methods. Effects of baffle installation are studied. The problems of forced vibrations are reduced to solving the systems of second order ordinary differential equations. For parametric vibrations the system of Mathieu equations is obtained. The numerical simulation of free surface elevations at different loadings and baffle configurations is accomplished. Beat phenomena effects are considered under lateral harmonic excitations. The phenomenon of parametric resonance is examined under longitudinal harmonic excitations.
Journal of Fluids and Structures, 2010
In this paper, a numerical-experimental study of the overall dynamical response of elevated spherical tanks subjected to horizontal base motion is presented. The main objective is to gain insight in the physical response of this particular structural typology widely used in the petrochemical industry as liquefied petroleum gas (LPG) containers. In order to identify the natural frequencies of the modes that mainly contribute to the response, experimental free vibration tests on an elevated spherical tank model for different liquid levels were carried out. Next, a numerical model that takes into account the coupling between fluid and structure was developed and validated against the experimental results. A very good agreement between experimental and numerical results was obtained. The results obtained show the influence of liquid levels on natural frequencies and indicate that the sloshing has a significant effect on the dynamical characteristics of the analyzed system. In order to obtain a good representation of the overall dynamical behaviour of the system by means of a simplified lumped mass model, a minimum of three masses is suggested. Finally, appropriate names of these three masses are proposed in the present paper.
Coupled vibration analysis of fluid-filled cylindrical shells using the wave propagation approach
Applied Acoustics, 2001
The coupled structural-acoustic analysis of ®nite¯uid-®lled cylindrical shells is presented using the wave propagation method. For uncoupled analysis the natural frequencies of the shell by the present method are compared with the results available in the literature. For coupled analysis the comparisons of the frequencies by the present method and numerical ®nite element method boundary element method (FEM/BEM) are carried out. Through the comparisons it is possible to conclude that the present method is correct. It is a simple, noniterative and relatively less computationally intensive method. It is shown that the¯uid eect on the shell is signi®cant. Ignorance of the¯uid eect will lead to large errors in the vibration analysis of¯uid-®lled shells.
Investigation of submerged structures flexibility on sloshing frequency
In this study, the boundary element method-finite element method (BEM-FEM) model is employed to investigate the sloshing and flexibility terms of elastic submerged structures on the behavior of a coupled domain. The methods are finite element and boundary elements which are utilized for structural dynamic and sloshing modeling, respectively. The applied models are used to assess dynamic parameters of a fluid-structure system. Based on the proposed model, a code is developed which can be applied to an arbitrary two-and three-dimensional tank with an arbitrarily shaped elastic submerged structure. Results are validated based on the existing methods represented in the literature and it is concluded that the absolute relative deviation is lower than 2%. Finally, the interactive influences of submerged components which are more meaningful are investigated.
Sloshing in a vertical circular cylindrical container with a vertical baffle
American Society of Mechanical Engineers, Fluids Engineering Division (Publication) FEDSM, 2010
The linear problem of liquid sloshing in a cylindrical container with a vertical baffle is considered in the present paper. In this study, a theoretical oriented approach is developed for calculating the natural frequencies of liquid. The baffle is a thin-walled and open-ended cylindrical shell that is concentrically placed and partially submerged inside the container. The free surface of liquid is assumed to be perpendicular to axis of the container and is divided into two parts by the baffle. The method also captures the singular asymptotic behavior of the velocity potential at the sharp baffle edge. The liquid is assumed to be incompressible and inviscid and the method uses matched eigenfunction expansions and Galerkin expansions to derive unknown coefficients presented in the velocity potential series. A finite element analysis is also used to check the validity of the proposed method. The effects of some important parameters of system are also considered on the sloshing frequencies.