| ORIGINAL ARTICLES |
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| Year : 2016 | Volume
: 1
| Issue : 2 | Page : 75-79 |
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Overstable convection in a double-diffusive, salt-stratified system heated from below
Karim Alwani Choubani1, Mohammed Abdulrahman Almeshaal2
1 Department of Mechanical, Riyadh College of Technology, Technical and Vocational Training Corporation, Riyadh, Saudi Arabia
2 Department of Mechanical Engineering, College of Engineering, Al Imam Mohammad Ibn Saud Islamic University, Riyadh, Saudi Arabia
Correspondence Address:
Karim Alwani Choubani
Department of Mechanical, Riyadh College of Technology, Technical and Vocational Training Corporation, Riyadh
Saudi Arabia
 Source of Support: None, Conflict of Interest: None  | Check |
DOI: 10.4103/ijas.ijas_29_16
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Introduction: The salt-stratified solution destabilized by bottom heating is a double-diffusive system, which is characterized by conditions similar to those found in salt gradient solar ponds. Although many of its features are well understood, controversy still exists concerning the mechanisms responsible for the growth of the first mixed layer. This growth strongly influences overall system performance. The solar pond is a complex system that is coupled to ambient conditions and where several different inputs can destabilize the stratification. This complexity cannot be reflected in the idealized analytical description of the mixing mechanisms. In spite of these difficulties, the experimental description seemed necessary. Our objective is to make a laboratory scale flow visualization experiments using shadowgraph, to understand the occurrence of overstability and the layer motion in a simulated solar ponds. Laboratory experiments were made to investigate further the stability and occurrence of convective regimes, as a function of density and heat constraints.
Methodology: In this paper, the overstable convection in a linearly salt-stratified system with a free surface and heated from below at constant temperature is studied. In the experimental studies, almost the same conditions and same stability parameter that we can find in a real salt-stratified solar pond was considered.
Results: It is found that the oscillatory motion appeared in the bottom of the stratification seems to be the main mechanism responsible for the growth of the first mixed layer which strongly influences overall system performance.
Conclusion: In this work, the onset and the development of the first mixed layer were studied for small stability parameter Λ. No investigation has been performed, to our knowledge, regarding the occurrence of overstability for small values of Λ. |
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