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Periodic Boundary Condition Tutorial

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Old   May 23, 2013, 11:55
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Amrita Lonkar
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SU2 now adds halo cells to only one side of the mesh. We do not require two sets of halo cells, and the information is exchanged between the set of halo cells, and a set of interior points on the other side of the mesh.
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Old   May 23, 2013, 21:23
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Quote:
Originally Posted by Amrita Lonkar View Post
SU2 now adds halo cells to only one side of the mesh. We do not require two sets of halo cells, and the information is exchanged between the set of halo cells, and a set of interior points on the other side of the mesh.
In a cfg file, the sender and receiver is define twice and the PBC program calculates twice.

Is the added halo cells a copy of the set of interior points on the other side?
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Old   April 17, 2015, 05:51
Default Problems with periodic boundary condition
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*bump*

It has been a while since the last post in this thread, but for me it seemed suitable to post it here since this thread is the only one I could find on the SU2 part of this forum considering periodic boundary conditions.

I'm trying to do a relatively simple flow analysis of a Caradonna & Tung rotor for compressible, inviscid rotating flow at 2500 rpm. Hence, this case is almost similar to the case provided in the Test Cases, I'm just using my own mesh instead of the one provided in the Test Cases. The main difference is that I try to run this case using a periodic boundary condition, which should be possible given that the situation is axisymmetric. Unfortunately, I'm experiencing some issues with this. First of all, the SU2_PBC module seems to have disappeared from the 3.2 version, is this correct? I couldn't find it on the Github page. Luckily my supervisor still has the 3.1 version installed next to the newest one, this version still includes SU2_PBC. I have adapted the mesh using the SU2_PBC executable from his V3.1 and then I used my own V3.2 to run the CFD simulation. For the first ~30 iterations everything seems to go well and it seems to converge nicely, but afterwards the residuals start to increase and the simulation diverges. I have already had to add a shaft at the rotation axis to prevent mismatches in the mesh after running SU2_PBC, such that my mesh looks similar to the case presented here: http://www.task.gda.pl/files/quart/T...4/tq312j-e.pdf. Also see the screenshot that I've attached (from Pointwise)

So, does anybody know what I can try to do in order to solve this? I've tried copying this mesh and rotating it 180 degrees about the x-axis to obtain the "full" grid in order to check if this might yield some new information, but the CFD simulation using this mesh converges normally. I've also attached a view from the periodic_halo.plt file that SU2_PBC gives as output. It only shows halo cells on one of the periodic boundaries, is this correct? In the configuration file I have defined the MARKER_PERIODIC both ways so this shouldn't be the problem:

MARKER_PERIODIC= ( periodic1, periodic2, 0.0, 0.0, 0.0, -180.0, 0.0, 0.0, 0.0, 0.0, 0.0, periodic2, periodic1, 0.0, 0.0, 0.0, +180.0, 0.0, 0.0, 0.0, 0.0, 0.0 )

Running the simulation without adapting the mesh doesn't help either; the simulation starts but it already has non-physical points from the beginning and the calculation quickly diverges.

Thanks in advance for your help!
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File Type: jpg mesh_caradonnatung.jpg (44.4 KB, 4 views)
File Type: jpg mesh_caradonnatung_halocells.jpg (96.2 KB, 4 views)
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