2002 Fiscal Year Final Research Report Summary
Numerical Analyses of Environmental Double Diffusive Natural Convection
| Project/Area Number |
12650218
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| Research Category |
Grant-in-Aid for Scientific Research (C)
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| Allocation Type | Single-year Grants |
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| Section | 一般 |
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| Research Field |
Thermal engineering
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| Research Institution | Toyama National College of Technology |
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Principal Investigator |
KAMAKURA Katsuyoshi Department of Chemical and Bio-chemical Engineering, Professor, 物質工学科, 教授 (40042832)
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| Project Period (FY) |
2000 – 2002
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| Keywords | Double diffusion / Salt-finger / Plume / Freezing / Interleaving / Natural convection |
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| Research Abstract |
Double diffusive natural convection are formed owing to both temperature and concentration differences under a gravitational field, and occurs in engineering processes such as crystal growth processes, melting or freezing of ice in an aqueous solution and roll-over phenomenon. Moreover, the phenomena may occur in various environmental situations such as chimney, heat island and mixing between hot factory waste water and cold river water. The numerical analyses of double-diffusive convection were carried out for the various environmental situations.
(1) Mixing phenomena
The mixing between hot solution and cold water was studied for the phenomena such as salt-finger, interleaving and saline wedge. In result, buoyancy ratio between thermal and solutal buoyancies was important for the mixing due to the salt-finger.
(2) Plume phenomena
A double diffusive plume in a cubic cavity heated from a central square part on the bottom were numerically studied. In the case of heating from entire bottom, a concentration stratified layer was formed near the bottom and a strong central and several weak plumes occurred with time. In the case of heating from a part of bottom, one or four plumes were directly formed from the bottom.
(3) Freezing in aqueous solution
In the case of lateral freezing, a thin boundary layer of concentration was formed near the moving boundary and the solute was accumulated near the bottom of the vessel. In the case of freezing from surface, salt-finger phenomena occurred and the solute was accumulated near the bottom of the vessel.
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