| Autor: |
Saravanan, S., Sivakumar, T. |
| Předmět: |
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| Zdroj: |
Physics of Fluids; Mar2010, Vol. 22 Issue 3, p034104, 15p, 2 Charts, 9 Graphs |
| Abstrakt: |
The effect of vibrations on the onset of convection in a horizontal fluid saturated porous layer heated either from below or from above is investigated. Vertical vibrations are considered with arbitrary amplitude and frequency. The Brinkman model of flow through porous media is used to describe the non-Darcian effect and the Oberbeck–Boussinesq approximation is invoked. Both continued fraction and Hill’s infinite determinant methods are used to determine the convective threshold for the stress free and rigid boundaries with the aid of Floquet theory. The marginal curves exhibiting synchronous and subharmonic resonant regions of dynamic instability and their critical boundaries are determined. The results obtained for Da=10-1 corresponding to the Brinkman regime is compared with Da=10-4 corresponding to the Darcy regime. It is demonstrated that vibrations can produce a stabilizing or a destabilizing effect depending on their amplitude and frequency for a porous layer heated from below. However in the case of a porous layer heated from above vibrations of increasing amplitude always result in a destabilizing effect irrespective their frequency. It is also shown that an increase in Da/φ, the ratio of Darcy number to porosity restricts competition between the synchronous and subharmonic modes to a lower range of vibrational frequencies. The present study reproduces already established results in the literature as particular cases. [ABSTRACT FROM AUTHOR] |
| Databáze: |
Complementary Index |
| Externí odkaz: |
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