Onset of natural convection induced by bottom-up transient mass diffusion in porous media

The theory of convection induced by transient mass diffusion in porous media is advanced and verified by computational fluid dynamics (CFD) simulation. A theory of the onset of buoyancy convection and a new transient Rayleigh number were derived. 2D time-dependent simulations were conducted for bott...

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Main Authors: Tan, Ka Kheng, Tan, Ye Wan, Choong, Thomas Shean Yaw
Format: Article
Language:English
Published: Elsevier 2009
Online Access:http://psasir.upm.edu.my/id/eprint/15940/1/Onset%20of%20natural%20convection%20induced%20by%20bottom.pdf
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author Tan, Ka Kheng
Tan, Ye Wan
Choong, Thomas Shean Yaw
author_facet Tan, Ka Kheng
Tan, Ye Wan
Choong, Thomas Shean Yaw
author_sort Tan, Ka Kheng
collection UPM
description The theory of convection induced by transient mass diffusion in porous media is advanced and verified by computational fluid dynamics (CFD) simulation. A theory of the onset of buoyancy convection and a new transient Rayleigh number were derived. 2D time-dependent simulations were conducted for bottom–up diffusion of methane gas in a porous medium pre-saturated with air. Sand particles with diameter ranged from 0.003 to 0.006 m were used as the porous media. The average maximum transient Rayleigh number for the onset of convection in the simulations was found to be 29.7, which was quite close to the theoretical value of 27.1. The critical times, critical depths of gas penetration and wavelengths were predicted accurately. It was found that the mass transfer may be driven by simultaneous diffusion and buoyancy convection after the onset. The rate of mass transfer for the convection phase was over three times that of pure diffusion.
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spelling upm.eprints-159402016-11-30T03:28:00Z http://psasir.upm.edu.my/id/eprint/15940/ Onset of natural convection induced by bottom-up transient mass diffusion in porous media Tan, Ka Kheng Tan, Ye Wan Choong, Thomas Shean Yaw The theory of convection induced by transient mass diffusion in porous media is advanced and verified by computational fluid dynamics (CFD) simulation. A theory of the onset of buoyancy convection and a new transient Rayleigh number were derived. 2D time-dependent simulations were conducted for bottom–up diffusion of methane gas in a porous medium pre-saturated with air. Sand particles with diameter ranged from 0.003 to 0.006 m were used as the porous media. The average maximum transient Rayleigh number for the onset of convection in the simulations was found to be 29.7, which was quite close to the theoretical value of 27.1. The critical times, critical depths of gas penetration and wavelengths were predicted accurately. It was found that the mass transfer may be driven by simultaneous diffusion and buoyancy convection after the onset. The rate of mass transfer for the convection phase was over three times that of pure diffusion. Elsevier 2009-04-04 Article PeerReviewed application/pdf en http://psasir.upm.edu.my/id/eprint/15940/1/Onset%20of%20natural%20convection%20induced%20by%20bottom.pdf Tan, Ka Kheng and Tan, Ye Wan and Choong, Thomas Shean Yaw (2009) Onset of natural convection induced by bottom-up transient mass diffusion in porous media. Powder Technology, 191 (1-2). pp. 55-60. ISSN 0032-5910; ESSN: 1873-328X 10.1016/j.powtec.2008.09.008
spellingShingle Tan, Ka Kheng
Tan, Ye Wan
Choong, Thomas Shean Yaw
Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title_full Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title_fullStr Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title_full_unstemmed Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title_short Onset of natural convection induced by bottom-up transient mass diffusion in porous media
title_sort onset of natural convection induced by bottom up transient mass diffusion in porous media
url http://psasir.upm.edu.my/id/eprint/15940/1/Onset%20of%20natural%20convection%20induced%20by%20bottom.pdf
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