Natural convection in an enclosure with temporally- and spatially-varying thermal boundary conditions시간 및 공간적 변동 열경계조건이 주어진 밀폐공간내의 자연대류

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First, a numerical study is made of the finite-wall effect in the benchmark-configuration buoyant convection in a square cavity at large Rayleigh number. A general formulation, with one vertical sidewall of finite thickness and thermal conductivity, is presented. In the first place, the finite-wall effect for the case of non-pulsating boundary temperature condition is delineated. The energy balance consideration, together with the preceding empirical correlations, leads to a simple formula to predict the temperature at the interior surface of the finite-thickness wall. The analytical predictions are shown to be consistent with the results of full-dress Navier-Stokes numerical solutions. Next, the finite-wall effect for the case of pulsating boundary temperature condition is explored. The numerical results illustrate that the amplitude of oscillating Nusselt number, A(Nu), at the central plane peaks at a particular pulsation frequency. This has been interpreted to be a manifestation of resonance. The finite-wall effect on the shift of resonance frequency is discussed. The temperature oscillation at the interior surface of the solid wall is examined, and the convection-modified model is introduced to describe the alteration in the temperature contrast across the fluid portion. The estimation of the resonance frequency, based on the internal gravity oscillations, is shown to be in accord with the Navier-Stokes numerical solutions. Second, a numerical investigation is made of three-dimensional natural convection of a Boussinesq-fluid in a vertically-mounted cylindrical container. The boundary conditions are such that the wall temperature $\theta_\Sigma$ is inhomogeneous in the horizontal azimuthal direction but $\theta_\Sigma$ increases in the vertical direction. Interest is confined to flows with globally-stable stratifications and with substantial azimuthal variations in thermal boundary conditions. Comprehensive numerical solutions to the Navier-Stokes equati...
Advisors
Hyun, Jae-Minresearcher현재민researcher
Description
한국과학기술원 : 기계공학전공,
Publisher
한국과학기술원
Issue Date
2002
Identifier
174473/325007 / 000975347
Language
eng
Description

학위논문(박사) - 한국과학기술원 : 기계공학전공, 2002.2, [ [xvi], 127 p ]

Keywords

finite thickness wall; resonance; enclosure; natural convection; three-dimensional; 유한한 두께의 벽; 3차원 수치해석; 유동공진; 시간 및 공간적 변동 열경계조건; 밀폐공간내의 자연대류

URI
http://hdl.handle.net/10203/43116
Link
http://library.kaist.ac.kr/search/detail/view.do?bibCtrlNo=174473&flag=dissertation
Appears in Collection
ME-Theses_Ph.D.(박사논문)
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