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Natural Convection Simulation - buoyantSimpleRadiation - Convergence Problem

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Old   June 9, 2010, 07:24
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Francois Gallard
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Ok, that is what I thought.
Could you try to put fixedValue 100 000 at the bottom and zeroGradient at the top for the pressure boundary conditions ?
The pressure is the motor of the flow with the buoyancy effect, as long as it is incorrect, the computation will not converge.
Francois.
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Old   June 10, 2010, 01:55
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MSarkar
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Hello Francois,

I tried that fixedValue 100 000 at bottom and zeroGradient at top but it did not give me any good results. The pressure and velocity fields are unrealistic. Pressure and velocity fields are attached below. I am trying some other pressure boundary conditions. If you have any other suggestions, please let me know.

Thanks and Regards
M. Sarkar
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File Type: jpg P.jpg (16.7 KB, 30 views)
File Type: jpg U.jpg (15.3 KB, 22 views)
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Old   June 10, 2010, 04:51
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Francois Gallard
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Hello,
Could you please rescale the pressure field between 100 000 and 100 010 ? I have the impression that now the hydrostatic gradient is correct. You have something weird at the angle but that could come from something else. Could you share all your boundary, system and constant files ?

Cheers,

François
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Old   June 10, 2010, 06:21
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Hi,

Yes I can rescale the pressure field but there is a glitch in the corner and I guess because of that it is not predicting velocity and temperature fields correctly. Anyway I will rescale it and post it later. I am attaching the 0, constant and system files as you requested. If I am wrong anywhere, please let me know.

Thanks
M. Sarkar
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File Type: gz 0.tar.gz (1.7 KB, 13 views)
File Type: gz system.tar.gz (1.2 KB, 5 views)
File Type: gz constant.tar.gz (1.6 KB, 5 views)
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Old   June 10, 2010, 08:11
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Arjun
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Okay , i decided to add bouss. method to inavier just to see how your problem works.

Here are some plots after running with iNavier
den = 1.225
Tref = 288
beta = 2.1E-4
visc = 1.789E-5

Temperature



Pressure



y vel




I believe these results look alright because something similar i got from Fluent too.


Please note that this is very first thing i ran with iNavier in name of bouss. model. So iNavier is not tested.


About convergence, i noticed that normalised residual is not good idea in this case to judge about convergence because normalised residual work by deviding maximum error found in first 5 or 10 iterations. But in this case velocity field is zero in the start and there is no flow in or out. So initial abs residual is very low. Which increases with iterations and then fall down.
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Old   June 15, 2010, 05:18
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Hi Arjun,

I did not see any result files here. Could you please upload your results? Did you use OpenFOAM-1.6.x for this simulation? I am sorry, I did not understand what is that iNavier you mentioned? If you use OF-1.6.x, which solver did you use, buoyantSimpleRadiatioFoam or something else?
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Old   June 15, 2010, 09:36
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Quote:
Originally Posted by msarkar View Post
Hi Arjun,

I did not see any result files here. Could you please upload your results? Did you use OpenFOAM-1.6.x for this simulation? I am sorry, I did not understand what is that iNavier you mentioned? If you use OF-1.6.x, which solver did you use, buoyantSimpleRadiatioFoam or something else?

i uploaded it on flickr and probably that is not visible to you. Coudl you give me your email i will mail you tecplot file.
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Old   June 16, 2010, 02:08
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Quote:
Originally Posted by arjun View Post
i uploaded it on flickr and probably that is not visible to you. Coudl you give me your email i will mail you tecplot file.
Hi Arjun,

My email id is below, please send me the files. If it is possible, send me the files in .jpg or .png format. I do not have Techplot. Can I open the files you mentioned using paraview? You did not mention anything about the tool you used to simulate this problem. I guess you used OF-1.6.x.



Last edited by msarkar; June 16, 2010 at 06:21.
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Old   June 16, 2010, 05:19
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Quote:
Originally Posted by msarkar View Post
Hi Arjun,

My email id is below, please send me the files. If it is possible, send me the files in .jpg or .png format. I do not have Techplot. Can I open the files you mentioned using paraview? You did not mention anything about the tool you used to simulate this problem. I guess you used OF-1.6.x.

email: mita.sarkar@airbus.com

i will email, it is on my other computer so might take a while.

About tecplot, there is one beautiful tool people do not use:

https://wci.llnl.gov/codes/visit/home.html

download it for tecplot Files.

I could send you paraview based files too but i export ensight gold format and somehow paraview goofs up when dealing with 2D data. In three D things seems to be alright.

About tool i used (iNavier), it is just a small code i wrote this reads mesh files in fluent format and runs segreggated SIMPLE algorithm.

I am working on releasing next version but still busy doing documentations etc etc. So still not in public domain. I will email you exe though, you could play with it.
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Old   June 16, 2010, 06:12
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i sent email , read the doc, please understand that solver is still under testing.
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Old   June 16, 2010, 06:21
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i sent email , read the doc, please understand that solver is still under testing.
Hi Arjun,

Sorry to request you again. Please send me the files in my other email id. I did not receive your email. My company email system quarantined it as it contained an attachment which is against the company policy.

email: mita.sarkar@gmail.com

So you did not use OpenFOAM but anyway I can look at your results.
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Old   June 16, 2010, 06:23
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Quote:
Originally Posted by msarkar View Post
Hi Arjun,

I am sorry to request you again. Please send me the files in my other email id. I did not receive your email. My company email system quarantined it as it contained an attachment which is against the company policy.

email: mita.sarkar@gmail.com

do you have anything other than gmail because my attachment contains exe and gmail does not allow it.

This is why i do not use gmail.
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Old   June 16, 2010, 06:27
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Hello,

I used second order schemes (Gauss linear for all div terms) and used 100x100 cells in your blocks instead of 50x50, used the same boundary conditions and get rid of that pressure problem. The results are still not ok because of the Epsilon equation but there is still some work to do. I keep you aware.

Francois
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