A Wave Equation Approach to Numerical Simulation of Natural Convection in Rectangular Enclosures PDF Download

Author: Kehinde Omobola Ladipo
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ISBN:
Category : Heat
Languages : en
Pages : 242

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Author: Charles Randall Walker
Publisher:
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Category : Buildings
Languages : en
Pages : 150

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Author's abstract: Numerical simulation was used to investigate natural convection in horizontal and vertical enclosures with and without an internal heat source. Natural convection in rectangular enclosures is found in many real-world applications. Included in these applications are the energy efficient design of buildings, operation and safety of nuclear reactors, solar collector design, passive energy storage, heat transfer across multi-pane windows, thermo-electric refrigeration and heating devices, and the design-for-mitigation of optical distortion in large- scale laser systems. Considering all these applications, especially controlling heat transfer in nuclear power plants, knowledge and research results of natural convection in enclosure play a vital role in environmental impact management studies. This study simulated horizontal enclosures heated from below (configuration 1) and vertical enclosures heated from the side (configuration 2) with a variety of different aspect ratios (AR) and Rayleigh numbers (Ra). Each aspect ratio (1, 2, 4, 6, 8, and 10) was examined using different sets of Rayleigh numbers. The first numerical experiment used only external Rayleigh number (RaE = 2×104, 2×105, and 2×106) which simulated natural convection in enclosures for outside temperature gradient only. The second case used a constant external Rayleigh number (RaE = 2×105) with a changing internal Rayleigh number (RaI = 2×104, 2×105, and 2×106). The third simulation used a constant internal Rayleigh number (Ra I = 2×105) and a changing external Raleigh number (RaE = 2×104, 2×105, and 2×106). All three cases were simulated for each configuration and at each aspect ratio. The streamline and isotherm flow patterns were created to reflect each case. The average heat flux ratio and convection strength were also calculated. Tests with the external temperature gradient only confirmed previous studies. There were many notable outcomes in this study which are discussed in the main body of this thesis work. When RaE> RaI, the results were similar to the study with a varying external Rayleigh number (RaE) and no internal heat source.

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Category :
Languages : en
Pages :

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Numerical solutions have been obtained for two-dimensional free convective flow in rectangular and annular cavities using the strongly implicit procedure (SIP) and the cyclic reduction-fast Fourier transform (CR-FFT) technique. Rayleigh numbers range from 104 to 106, Prandtl numbers from 0.713 to 103, radius ratios from 1 to 3 (annular cavities), and aspect ratios (height/width) from 1 to 15. Motion is generated by either uniformly heating the bottom wall or heating a vertical wall (nondimensional temperature of 1) and cooling the opposite wall (nondimensional temperature of 0). Both time-dependent and steady state solutions confirm results previously obtained by others. The computational speed of the SIP and CR-FFT methods is very fast. Because SIP uses a common set of matrix algorithms, the governing equations of motion can be solved simultaneously without major modification to the method for each equation.

Author: Panayiotis S. Theodossopoulos
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 266

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Author: Douglas James Silva
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ISBN:
Category : Heat
Languages : en
Pages : 428

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Author: A. Gadgil
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Category :
Languages : en
Pages : 16

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The present paper describes a verification of CONVEC2 for single-zone geometries by comparison with the results of two natural convection experiments performed in small-scale rectangular enclosures. These experiments were selected because of the high Rayleigh numbers obtained and the small heat loss through the insulated surfaces. Comparisons are presented for (1) heat transfer rates, (2) fluid temperature profiles, and (3) surface heat flux distributions.

Author: Mehrdad Rahdar
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Category :
Languages : en
Pages : 0

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Category : Aeronautics
Languages : en
Pages : 594

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Author: A. Gadgil
Publisher:
ISBN:
Category :
Languages : en
Pages : 16

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The present paper describes a verification of CONVEC2 for single-zone geometries by comparison with the results of two natural convection experiments performed in small-scale rectangular enclosures. These experiments were selected because of the high Rayleigh numbers obtained and the small heat loss through the insulated surfaces. Comparisons are presented for (1) heat transfer rates, (2) fluid temperature profiles, and (3) surface heat flux distributions.

Author: Joseph Bayne Schroeder
Publisher:
ISBN:
Category : Heat
Languages : en
Pages : 330

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