Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium
This study numerically investigated the validity of the local thermal equilibrium model for free convection over a horizontal cylinder embedded in an infinitely packed bed of spherical particles saturated with Newtonian fluid. The local thermal non-equilibrium and Forchhemimer-Brinkman extended Darc...
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| Format: | Article |
| Language: | English |
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Elsevier
2023-01-01
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| Series: | Results in Physics |
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| Online Access: | http://www.sciencedirect.com/science/article/pii/S2211379722007264 |
| _version_ | 1797950715716435968 |
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| author | Behnam Keshavarzian Habib-Olah Sayehvand |
| author_facet | Behnam Keshavarzian Habib-Olah Sayehvand |
| author_sort | Behnam Keshavarzian |
| collection | DOAJ |
| description | This study numerically investigated the validity of the local thermal equilibrium model for free convection over a horizontal cylinder embedded in an infinitely packed bed of spherical particles saturated with Newtonian fluid. The local thermal non-equilibrium and Forchhemimer-Brinkman extended Darcy model were used by considering the boundary-layer theory assumptions and were solved with the implicit Keller box finite difference scheme. The governing parameters considered are the porosity, thermal conductivity ratio, Rayleigh number, Prandtl number, the ratio of cylinder diameter to spherical particle diameter and Biot number. The results showed the two parameters of conductivity ratio and Biot number can significantly affect the other parameters. For low Biot number and conduction coefficient ratio, the local thermal non-equilibrium assumption was inapplicable in almost all cases. Significantly, for high values of the conductivity ratio and Biot number, the assumption that the fluid and solid matrix are isothermal, could be used in almost all cases studied. Furthermore, increasing the amount of Rayleigh number, Porosity and Prandtl increased the temperature difference between the solid and fluid phases. In addition, increasing the ratio of cylinder diameter to particle diameter reduced the temperature difference between the two phases. The average temperature difference between fluid and solid can have the most changes as follows: It can experience 200% growth when the Prandtl number changes from 2 to 7. Also, it can reduce by 33% by increasing the Bio number from 0.01 to 10. In addition, the temperature difference of two phases can be increased by 7 and 0.5 times by increasing the porosity from 0.25 to 0.85 and increasing the ratio of cylinder diameter to particle diameter from 20 to 100, respectively. |
| first_indexed | 2024-04-10T22:20:37Z |
| format | Article |
| id | doaj.art-2b797af6c7a04fcb99e1c94b6b581b2e |
| institution | Directory Open Access Journal |
| issn | 2211-3797 |
| language | English |
| last_indexed | 2024-04-10T22:20:37Z |
| publishDate | 2023-01-01 |
| publisher | Elsevier |
| record_format | Article |
| series | Results in Physics |
| spelling | doaj.art-2b797af6c7a04fcb99e1c94b6b581b2e2023-01-18T04:30:26ZengElsevierResults in Physics2211-37972023-01-0144106112Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous mediumBehnam Keshavarzian0Habib-Olah Sayehvand1Mechanical Engineering Department, Bu-Ali Sina University, Hamedan, IranCorresponding author.; Mechanical Engineering Department, Bu-Ali Sina University, Hamedan, IranThis study numerically investigated the validity of the local thermal equilibrium model for free convection over a horizontal cylinder embedded in an infinitely packed bed of spherical particles saturated with Newtonian fluid. The local thermal non-equilibrium and Forchhemimer-Brinkman extended Darcy model were used by considering the boundary-layer theory assumptions and were solved with the implicit Keller box finite difference scheme. The governing parameters considered are the porosity, thermal conductivity ratio, Rayleigh number, Prandtl number, the ratio of cylinder diameter to spherical particle diameter and Biot number. The results showed the two parameters of conductivity ratio and Biot number can significantly affect the other parameters. For low Biot number and conduction coefficient ratio, the local thermal non-equilibrium assumption was inapplicable in almost all cases. Significantly, for high values of the conductivity ratio and Biot number, the assumption that the fluid and solid matrix are isothermal, could be used in almost all cases studied. Furthermore, increasing the amount of Rayleigh number, Porosity and Prandtl increased the temperature difference between the solid and fluid phases. In addition, increasing the ratio of cylinder diameter to particle diameter reduced the temperature difference between the two phases. The average temperature difference between fluid and solid can have the most changes as follows: It can experience 200% growth when the Prandtl number changes from 2 to 7. Also, it can reduce by 33% by increasing the Bio number from 0.01 to 10. In addition, the temperature difference of two phases can be increased by 7 and 0.5 times by increasing the porosity from 0.25 to 0.85 and increasing the ratio of cylinder diameter to particle diameter from 20 to 100, respectively.http://www.sciencedirect.com/science/article/pii/S2211379722007264Porous mediaBoundary layerFree convectionKeller boxNon-DarcyLocal Thermal Non-Equilibrium |
| spellingShingle | Behnam Keshavarzian Habib-Olah Sayehvand Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium Results in Physics Porous media Boundary layer Free convection Keller box Non-Darcy Local Thermal Non-Equilibrium |
| title | Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| title_full | Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| title_fullStr | Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| title_full_unstemmed | Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| title_short | Validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| title_sort | validation of the local thermal equilibrium assumption for free convection boundary layer flow over a horizontal cylinder embedded in an infinite saturated porous medium |
| topic | Porous media Boundary layer Free convection Keller box Non-Darcy Local Thermal Non-Equilibrium |
| url | http://www.sciencedirect.com/science/article/pii/S2211379722007264 |
| work_keys_str_mv | AT behnamkeshavarzian validationofthelocalthermalequilibriumassumptionforfreeconvectionboundarylayerflowoverahorizontalcylinderembeddedinaninfinitesaturatedporousmedium AT habibolahsayehvand validationofthelocalthermalequilibriumassumptionforfreeconvectionboundarylayerflowoverahorizontalcylinderembeddedinaninfinitesaturatedporousmedium |