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September 7, 2014, 08:06 |
natural convection
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#1 |
New Member
Other
Join Date: Aug 2014
Posts: 3
Rep Power: 11 |
hello everyone,
i'm having a problem with the convergence of the result of the simulation of the natural convection. Are there anyone have experience about it? |
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September 8, 2014, 01:38 |
hi
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#2 |
Member
Virendrasingh Pawar
Join Date: Jun 2013
Posts: 47
Rep Power: 12 |
i have some experience in multiphase buoyancy flows but not in natural convection.
Anyways i'll share few things: 1) My problem was flow through a pump sump ( open channel with pump at end) with surface air suction. This particular setup was very sensitive to initial solution so i first converged the solution with single phase setup and then used fluent's 'interpolate' feature to initialize the multiphase setup. Convergence issues were solved by this approach. If this process makes any sense in your problem, please try it out. 2) I found that steady state simulations produced absurd results so i had to stick to transient simulations. 3) At the end of this html file you'll find some guidelines for high Ra flows, see if that helps. html --> http://aerojet.engr.ucdavis.edu/flue...ug/node572.htm |
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September 11, 2014, 05:58 |
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#3 |
New Member
Kawis Somp
Join Date: Aug 2011
Posts: 1
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I also have an experience about natural convection but not sure that model is correct.
I used boussinesq model and specified operating density in operating condition. |
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September 17, 2014, 06:31 |
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#4 |
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Join Date: Aug 2014
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i also use boussinesq model for density but i think the operating density was defined in the properties of the material for fluid which i use here is oil. My problem is heat transfer by natural convection in the transformers. Do you have any idea about it?
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September 17, 2014, 11:50 |
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#5 | |
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Quote:
You can also try playing with gravity; set it at -1 and see if it seems to converge; increment it steadily till you converge at -9.8. Another thing to try is Adapting the mesh...go to Adapt->Region and manually adapt some part of the mesh. Make sure you're using PRESTO! discritization for pressure If all else fails, disable solving for the Flow equations under solution controls and try just solving for Energy first. Natural convection (and buyoncy driven flows in general) are some of the hardest simulations, so you have to be resilient. Expect having to run thousands of iterations to get a solution. Hope that helps. |
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September 17, 2014, 11:54 |
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#6 |
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Other
Join Date: Aug 2014
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Thank you . I'll try it now
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