The onset of transient convection in bottom heated porous media
The theory of transient convection in bottom heated porous media under constant heat flux (CHF) condition or fixed surface temperature (FST) condition is advanced and verified by computational fluid dynamics (CFD) simulations. The use of κ*, instead of κ m tends to artificially inflate the value of...
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| Format: | Article |
| Language: | English |
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Elsevier Science
2003
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| Online Access: | http://psasir.upm.edu.my/id/eprint/114575/ http://psasir.upm.edu.my/id/eprint/114575/1/114575.pdf |
| _version_ | 1848866534478315520 |
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| author | Tan, Ka-Kheng Sam, Torng Jamaludin, Hishamuddin |
| author_facet | Tan, Ka-Kheng Sam, Torng Jamaludin, Hishamuddin |
| author_sort | Tan, Ka-Kheng |
| building | UPM Institutional Repository |
| collection | Online Access |
| description | The theory of transient convection in bottom heated porous media under constant heat flux (CHF) condition or fixed surface temperature (FST) condition is advanced and verified by computational fluid dynamics (CFD) simulations. The use of κ*, instead of κ m tends to artificially inflate the value of Rayleigh number by about 30%. A new transient Rayleigh number for unsteady-state heat conduction was defined to predict the onset of transient convection in porous media, which were successfully simulated. The critical transient Rayleigh number from the simulation for CHF was about 29.60, which is close to the theoretical value of 27.1 calculated by Ribando and Torrance in 1976. In the case of FST, the critical transient Rac was found to be 30.9, which is close to the theoretical value of 32.3. The critical times of onset for simulations were predicted with good accuracy. The prediction of the critical wavelengths of the emerging plumes were fair for the 2D simulations. Any experiment to verify the linear stability analysis for thermal instability must simultaneously concur in the three eigenvalue parameters, namely the Biot number, the critical wavenumber and the corresponding critical Rayleigh number, apart from the physical boundaries. The average maximum transient Nusselt number was found to be 3.41 for CHF and 3.5 for FST respectively. |
| first_indexed | 2025-11-15T14:22:08Z |
| format | Article |
| id | upm-114575 |
| institution | Universiti Putra Malaysia |
| institution_category | Local University |
| language | English |
| last_indexed | 2025-11-15T14:22:08Z |
| publishDate | 2003 |
| publisher | Elsevier Science |
| recordtype | eprints |
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| spelling | upm-1145752025-03-05T00:59:09Z http://psasir.upm.edu.my/id/eprint/114575/ The onset of transient convection in bottom heated porous media Tan, Ka-Kheng Sam, Torng Jamaludin, Hishamuddin The theory of transient convection in bottom heated porous media under constant heat flux (CHF) condition or fixed surface temperature (FST) condition is advanced and verified by computational fluid dynamics (CFD) simulations. The use of κ*, instead of κ m tends to artificially inflate the value of Rayleigh number by about 30%. A new transient Rayleigh number for unsteady-state heat conduction was defined to predict the onset of transient convection in porous media, which were successfully simulated. The critical transient Rayleigh number from the simulation for CHF was about 29.60, which is close to the theoretical value of 27.1 calculated by Ribando and Torrance in 1976. In the case of FST, the critical transient Rac was found to be 30.9, which is close to the theoretical value of 32.3. The critical times of onset for simulations were predicted with good accuracy. The prediction of the critical wavelengths of the emerging plumes were fair for the 2D simulations. Any experiment to verify the linear stability analysis for thermal instability must simultaneously concur in the three eigenvalue parameters, namely the Biot number, the critical wavenumber and the corresponding critical Rayleigh number, apart from the physical boundaries. The average maximum transient Nusselt number was found to be 3.41 for CHF and 3.5 for FST respectively. Elsevier Science 2003 Article PeerReviewed text en http://psasir.upm.edu.my/id/eprint/114575/1/114575.pdf Tan, Ka-Kheng and Sam, Torng and Jamaludin, Hishamuddin (2003) The onset of transient convection in bottom heated porous media. International Journal of Heat and Mass Transfer, 46 (15). pp. 2857-2873. ISSN 0017-9310; eISSN: 0017-9310 https://linkinghub.elsevier.com/retrieve/pii/S0017931003000450 10.1016/S0017-9310(03)00045-0 |
| spellingShingle | Tan, Ka-Kheng Sam, Torng Jamaludin, Hishamuddin The onset of transient convection in bottom heated porous media |
| title | The onset of transient convection in bottom heated porous media |
| title_full | The onset of transient convection in bottom heated porous media |
| title_fullStr | The onset of transient convection in bottom heated porous media |
| title_full_unstemmed | The onset of transient convection in bottom heated porous media |
| title_short | The onset of transient convection in bottom heated porous media |
| title_sort | onset of transient convection in bottom heated porous media |
| url | http://psasir.upm.edu.my/id/eprint/114575/ http://psasir.upm.edu.my/id/eprint/114575/ http://psasir.upm.edu.my/id/eprint/114575/ http://psasir.upm.edu.my/id/eprint/114575/1/114575.pdf |