• Title, Summary, Keyword: Fluid-Coupled Cylinder

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Combined Thermal Radiation with Turbulent Convection Conjugate PCM Model (난류 대류를 도입한 고온 축열 시스템 모델의 열복사 전달에 관한 연구)

  • Kim, K.S.
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.7 no.4
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    • pp.556-565
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    • 1995
  • The physical model of interest is based upon the concentric cylinder, where the outside cylinder is filled with optically thick and high temperature phase change material(PCM). The fluid is flowing through the inside cylinder to transfer the appropriate energy. The fluid is flowing through the inside cylinder to transfer the appropriate energy. The governing equations for the phase change material including internal thermal radiation and for the turbulent transfer fluid have been employed and numerically solved. The optically thick phase change justifies the P-l spherical harmonics approximation, which is believed to be appropriate choice particularly for the much coupled problem like in this study. The solid/liquid interface, temperature distribution within the PCM and the heat flux from the PCM to the transfer fluid have been obtained and compared with those of laminar transfer fluid. The numerical results show that the turbulent transfer fluid accelerates the solid/liquid interface and results in the increase of heat transfer rate from the PCM. The internal thermal radiation within the PCM, however, does not always playa role to increase the heat transfer rate throughout the inside cylinder. It is believed that the combined heat flux has been picked up more in the inflowing area than in the pure conductive phase change material.

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Free Vibration Analysis of a Circular Plate Submerged in a Fluid-filled Rigid Cylinder (유체로 채워진 강체 실린더에 잠긴 원판의 고유진동 해석)

  • Jeong, Kyeong-Hoon;Choi, Suhn;Jhung, Myung-Jo
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • pp.921-925
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    • 2003
  • An analytical method for the free vibration of single circular plate submerged in a fluid-filled rigid cylindrical vessel was developed by the Rayleigh-Ritz method based on the Fourier-Bessel series expansion. It was assumed that the plate is clamped at an offcentered location of the cylinder, and the non-viscous incompressible fluid contained in the cylinder is bisected by the plate. It was found that the theoretical results can predict well the fluid-coupled natural frequencies with excellent accuracy comparing with the finite element analysis results. The offcentered distance effect on the natural frequencies was also observed.

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CFD-FSI simulation of vortex-induced vibrations of a circular cylinder with low mass-damping

  • Borna, Amir;Habashi, Wagdi G.;McClure, Ghyslaine;Nadarajah, Siva K.
    • Wind and Structures
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    • v.16 no.5
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    • pp.411-431
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    • 2013
  • A computational study of vortex-induced transverse vibrations of a cylinder with low mass-damping is presented. An Arbitrary Lagrangian-Eulerian (ALE) formulation of the Unsteady Reynolds-Averaged Navier-Stokes equations (URANS), along with the Spalart-Allmaras (SA) one-equation turbulence model, are coupled conservatively with rigid body motion equations of the cylinder mounted on elastic supports in order to study the amplitude and frequency response of a freely vibrating cylinder, its flow-induced motion, Vortex Street, near-wake flow structure, and unsteady loading in a moderate range of Reynolds numbers. The time accurate response of the cylinder from rest to its limit cycle is studied to explore the effects of Reynolds number on the start of large displacements, motion amplitude, and frequency. The computational results are compared with published physical experiments and numerical studies. The maximum amplitudes of displacements computed for various Reynolds numbers are smaller than the experimental values; however, the overall agreement of the results is quite satisfactory, and the upper branch of the limit-cycle displacement amplitude vs. reduced velocity response is captured, a feature that was missed by other studies. Vortex shedding modes, lock-in phenomena, frequency response, and phase angles are also in agreement with experiments.

Vortex-Induced Vibrations of a Circular Cylinder at Low Reynolds Numbers

  • Lee, Minhyung;Lee, Sung-Yeoul
    • Journal of Mechanical Science and Technology
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    • v.17 no.11
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    • pp.1628-1637
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    • 2003
  • The vortex-induced vibrations of a circular cylinder at low Reynolds (Re) numbers are simulated by applying a method of the two-dimensional computational fluid dynamics coupled with the structural dynamics based on the multi-physics. The fluid solver is first tested on the case of a fixed cylinder at Re$\leq$160, and shows a good agreement with the previous high-resolution numerical results. The present study then reports on the detailed findings concerning the vibrations of an elastic cylinder with two degrees of translational freedom for a number of cases in which Re is fixed at 200, a reduced damping parameter Sg=0.01, 0.1, 1.0, 10.0 and the mass ratio M$\^$*/ = 1, 10.

Vibration Measurements of an Intelligent Cantilever Beam in Contact with Fluid

  • Kwon, Tae-Kyu;Park, Seong-Hwa;Yu, Gye-Hyoung;Lee, Seong-Cheol
    • 제어로봇시스템학회:학술대회논문집
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    • pp.97.3-97
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    • 2002
  • This paper presents the vibration characteristics of an intelligent cantilever beam in contact with a fluid using a PZT actuator and PVDF film. The dynamic behaviors of a flexible beam-water interaction system are examined. The effect of the liquid level on free vibration of the composite beam in a partially liquid-filled circular cylinder is investigated. The coupled system is subject to an undisturbed boundary condition in the fluid domain. It was found that the coupled natural frequencies decreased with the fluid level for the identical composite beam due to added mass effect. In case of the free-free boundary condition, the natural frequency gently decreased at fluid water level betw...

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Characteristics of Coupled Acoustic Wave Propagation in Metal Pipe (금속 배관의 연성된 음향 전파 특성)

  • Kim, Ho-Wuk;Kim, Min-Soo;Lee, Sang-Kwon
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.32 no.3
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    • pp.267-273
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    • 2008
  • The circular cylinder pipes are used in the many industrial areas. In this paper, the acoustic wave propagation in the pipe containing a gas is researched. First of all, the theory for the coupled acoustic wave propagation in a pipe is investigated. Acoustic wave propagation in pipe can not be occurred independently between the wave of the fluid and the shell. It requires complicated analysis. However, as a special case, the coupled wave in a high density pipe containing a light density medium is corresponded closely to the uncoupled in-vacuo shell waves and to the rigid-walled duct fluid waves. The coincidence frequencies of acoustic and shell modes contribute to the predominant energy transmission. The coincidence frequency means the frequency corresponding to the coincidence of the wavenumber in both acoustic and shell. In this paper, it is assumed that the internal medium is much lighter than the pipe shell. After the uncoupled acoustic wave in the internal medium and uncoupled shell wave are considered, the coincidence frequencies are found. The analysis is successfully confirmed by the verification of the experiment using the real long steel pipe. This work verifies that the coupled wave characteristic of the shell and the fluid is occurred as predominant energy transmission at the coincidence frequencies.

Numerical simulation of flow past a rotating and rotary oscillating circular cylinder on unstructured meshes

  • Bai, Wei
    • Coupled systems mechanics
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    • v.2 no.2
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    • pp.191-214
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    • 2013
  • The unsteady flow past a circular cylinder which starts rotating or rotary oscillating impulsively from rest in a viscous fluid is investigated for Reynolds numbers Re=200 and 1000, rectilinear speed ratios ${\alpha}$ between 0.5 and 5.0, and forced oscillating frequencies $f_s$ between 0.1 and 2.0. Numerical solutions of the Navier-Stokes equations are obtained by using a finite volume method on an unstructured colocated grid. The objective of the study is to examine the effect of the rotating and rotary oscillating circular cylinder on the flow patterns and dynamics loads. The numerical results reveal that the $K\acute{a}rm\acute{a}n$ vortex street vanishes entirely behind the rotating cylinder when the ratio ${\alpha}$ exceeds the critical value, and the vortex shedding behind the rotary oscillating cylinder undergoes mainly three modes named 'synchronization', 'competition' and 'natural shedding' with the increase of $f_s$. Based on the amplitude spectra analysis of the lift coefficients, the regions of the classification of flow structure modes are presented, which provide important references for the flow control in the ocean engineering.

Preconditioning Method of a Finite Element Combined Formulation for Fluid-Structure Interaction (유체-구조물 상호작용을 위한 유한요소 결합공식화의 예조건화에 대한 연구)

  • Choi, Hyoung-Gwon
    • Transactions of the Korean Society of Mechanical Engineers B
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    • v.33 no.4
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    • pp.242-247
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    • 2009
  • AILU type preconditioners for a two-dimensional combined P2P1 finite element formulation of the interaction of rigid cylinder with incompressible fluid flow have been devised and tested by solving fluid-structure interaction (FSI) problems. The FSI code simulating the interaction of a rigid cylinder with an unsteady flow is based on P2P1 mixed finite element formulation coupled with combined formulation. Four different preconditioners were devised for the two-dimensional combined P2P1 finite element formulation extending the idea of Nam et al., which was proposed for the preconditioning of a P2P1 mixed finite element formulation of the incompressible Navier-Stokes equations. It was found that PC-III or PC-IV among them perform well with respect to computational memory and convergence rate for some bench-mark problems.

Effect of Fluid Added Mass on Vibration Characteristics and Seismic Responses of Immersed Concentric Cylinders (유체속에 잠긴 동축원통 구조물의 진동특성 및 지진응답에 대한 유체부가질량 영향)

  • 구경회;이재한
    • Journal of the Earthquake Engineering Society of Korea
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    • v.5 no.5
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    • pp.25-33
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    • 2001
  • For the seismic design and analysis of LMR(liquid metal reactor) being developed in Korea, it is necessary to develop the simple seismic analysis model including the fluid-structure interaction effects. In this paper, the theoretical backgrounds for the fluid added mass of the immersed concentric cylinders are investigated and the seismic analysis code using the Runge-Kutta algorithm, which can consider the fluid added mass matrix in system matrix, are developed to perform the time history seismic analysis. Form the coupled modal analysis and the seismic analysis for the simple immersed concentric cylinders, it is verified that the fluid added mass significantly affect the vibration characteristics and the seismic responses. Therefore the fluid coupled effects should be carefully considered in seismic response analysis of the immersed concentric cylinders.

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A Numerical Study of The Motion of a Circular Cylinder Suspended in a Square Enclosure (사각 밀폐계 내 자연대류에 의한 원형 실린더의 운동 특성에 관한 수치적 연구)

  • Son, Seong-Wan;Jeong, Hea-Kown;Ha, Man-Yeong;Yoon, Hyun-Sik
    • Korean Journal of Air-Conditioning and Refrigeration Engineering
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    • v.22 no.11
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    • pp.727-734
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    • 2010
  • The present study numerically investigates the motion of a solid body suspended in the square enclosure with natural convection. A two-dimensional circular cylinder levitated thermally has been simulated by using thermal lattice Boltzmann method(TLBM) with the direct-forcing immersed boundary method. To deal with the ascending, falling or levitation of a circular cylinder in natural convection, the immersed boundary method is expanded and coupled with the TLBM. The circular cylinder is located at the bottom of a square enclosure with no restriction on the motion and freely migrates due to the Boussinesq approximation which is employed for the coupling between the flow and temperature fields. For different density ratio between the cylinder and the fluid, the motion characteristics of the circular cylinder for various Grashof numbers have been carried out. The Prandtl number is fixed as 0.7.