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Overpredicted Trailing Edge Separation

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Old   March 5, 2013, 13:45
Default Overpredicted Trailing Edge Separation
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Hi SU2 users,
I am doing the 2d CFD validation case for the trailing edge separation over the NACA-4series single element airfoil with a low mach number.
The grid is very good C-type, fully structured max-y+ = 0.2, but the solution converges not well. I tried to used initially the JST scheme with multigrid (later on single grid), then switched to upwind scheme ROE_2nd_Order with and without multigrid no success. I also tried with smaller and larger CFL numbers. Last but not the least i used SA turbulence model and i am still using the SU2 v1.1.

I would really appreciate any kind of advise to improve the results, that i will attach later on together with the grid as snapshots.

Thanks in advance.
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Old   March 6, 2013, 11:18
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Quote:
Originally Posted by taxalian View Post
Hi SU2 users,
I am doing the 2d CFD validation case for the trailing edge separation over the NACA-4series single element airfoil with a low mach number.
The grid is very good C-type, fully structured max-y+ = 0.2, but the solution converges not well. I tried to used initially the JST scheme with multigrid (later on single grid), then switched to upwind scheme ROE_2nd_Order with and without multigrid no success. I also tried with smaller and larger CFL numbers. Last but not the least i used SA turbulence model and i am still using the SU2 v1.1.

I would really appreciate any kind of advise to improve the results, that i will attach later on together with the grid as snapshots.

Thanks in advance.
Hi,

Thanks a lot for your feedback, we are improving the code everyday, and every month we upload the current version of the code our webpage.

We are very concern about the importance of the V&V, and the SA has been fully validated.

In order to help you, could you please first download the current version of the code
http://su2.stanford.edu/download/svn/SU2_Rev1206.zip

You will find a folder called NACA0012_RANS, where you have the config file and mesh file that we are using for the NACA validation (http://turbmodels.larc.nasa.gov/naca0012_val_sa.html)

Thanks for using SU2
Best,

Francisco
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Old   March 6, 2013, 16:36
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Hi Fransico,

Thanks for sharing the current version of the code and the configuration file for the NACA0012 V&V case. I will try to sought out the problem and let you know about the progress soon.

Many thanks and regards.
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Old   March 11, 2013, 02:00
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Hi Fransico,
How do i compile the earlier attached current code version, as i am using cygwin in win7 to run SU2 v1.1. I have not able to compile this one. Waiting for your reply.

regards and thanks in advance.
SU2 user.
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Old   March 12, 2013, 02:24
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Hi,

Do you have access to Python in your cygwin environment? You could try to use the python build script to run the various makefiles. The script, build_SU2.py, can be found in the SU2Py/ directory.

There are also individual makefiles for the different modules that you can call directly. These are located in the corresponding config/ directories, i.e. SU2_CFD/config/.

Hope this helps!
Tom
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Old   March 17, 2013, 04:58
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Hello Fransico and Tom together,
I really appreciate your help and it helps me alot to resolve the problem by using the current SU2 version you provided and the Naca0012 config file to launch SU2 computation.

Well for the validation case i got pretty descent result compared to experiments and CFL3D predictions.
http://turbmodels.larc.nasa.gov/naca4412sep_val.html

See the attached cp distribution & mesh pictures. The SU2 results have been obtained using SA turbulence model, SST is under progress. I am compiling a kind of user guide kind of presentation which i will share with you guys. I think one can make a very good tutorial out of that and i am working on that.
Attached Images
File Type: jpg cfd_vs_exp_cp.jpg (38.5 KB, 24 views)
File Type: jpg SU2_mesh.jpg (88.9 KB, 36 views)
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Old   March 25, 2013, 06:42
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Sijal Ahmed Memon (turboenginner@gmail.com)
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How did you make this mesh?
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Old   March 25, 2013, 10:18
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Hi Fransico and Tom together,

See the attached file showing the comparison of SU2.SA result with existing CFL3D.SA & Experiment result for the validation of 2D NACA 4412 Airfoil Trailing Edge Separation (http://turbmodels.larc.nasa.gov/naca4412sep_val.html).

SU2 results compare very well with the existing CFD CFL3D results and with the experimental results.

I have used my own hybrid grid not the one provided on the website which is fully structured. The farfield is about 20c while the available grids contains about 100c dimensions. Nevertheless the results are very comparable and at the moment the computations have been carried out with SA turublence model.

Thanks and regards for your support and correspondence.
Attached Images
File Type: jpg cfd_vs_exp_u_profiles.jpg (69.2 KB, 26 views)
File Type: jpg cfd_vs_exp_v_profiles.jpg (63.8 KB, 20 views)
File Type: jpg cfd_vs_exp_upvp_profiles.jpg (60.2 KB, 22 views)
File Type: jpg cfd_vs_exp_field.jpg (40.1 KB, 26 views)
File Type: jpg o_mesh.jpg (90.6 KB, 26 views)
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Last edited by taxalian; March 25, 2013 at 11:04.
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Old   March 25, 2013, 11:14
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Sijal Ahmed Memon (turboenginner@gmail.com)
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It seems you made this mesh in gridgen...
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Old   March 26, 2013, 16:20
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taxalian,

Thank you for sharing this. We would be interested to see anything else that you prepare for this case.

Nice work!
Tom
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Old   March 28, 2013, 04:51
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Hi SU2 team,
Thanks for the reply, for sure i will submit the complete presentation upon completion of this validation study to SU2 developers team.

Thanks and regards.
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