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Old   June 10, 2009, 05:27
Default Heat transfer over displaced faces
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Sven Dietershagen
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In a Conjugated Heat Transfer Calculation we try to analyze the heat transfer from a fluid (blue in the picture) to our rotor solid (green and orange in the picture). Due to the way of or mesh generation our blade is not centered in the fluid zone but the blade root is constructed centered below the blade. So our solid fluid interface is displaced in theta direction (see attached picture). The pitch angles of all interface components are equal. Periodicity of the single components is set correctly.
After analyzing the result, we see that the heat transfer is only calculated in the geometrically overlapped areas. The non overlapped areas show no transfers as well as the parameter ‘nonoverlap fraction’ is 1 in this areas.
Does anyone ever had such problems and could give us a hint to solve it.
We are using Ansys CFX 11 + SP1.

Thanks
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Old   June 10, 2009, 08:11
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Glenn Horrocks
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Hi,

There has been enhancements to CHT modelling in V12. Not sure if it has addressed this problem but it might have. Regardless or whether it is fixed in the newer version you should move to V12 anyway.

Glenn Horrocks
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Old   June 15, 2009, 05:04
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Sven Dietershagen
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I cannot upgrade to v12 at the moment, because I am using a high performance grid at or university internal computing centre. Some licensing issues prevent the admins from updating to v12 at this time.
I have just built a simplified model with very coarse meshes and uploaded it to my webspace. There are two domains in this model, one fluid domain and one solid. Both are rotational periodic.
In Expertparameters I have set the parameters needed to run the partitioner with our complex model, so you can see what we want.
If you calculate the model you will see, that only the overlapped areas will perform heat transfer though there should be Heat transfer on the whole Interface area due to the periodicity

I would be very pleased if someone can provide me some advice.

Thanks
Sven
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Old   June 15, 2009, 06:51
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Glenn Horrocks
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Hi,

I think you may have found a shortcoming in V11 so I suspect you are stuck. I would talk to CFX support to confirm it. But the first thing they will say is to go to V12, as there has been some updates to GGIs and CHT so your problem might be fixed.

Don't waste your time trying to fix a problem that may have already been fixed in the current release.

And yes, the licensing changes in V12 has caused us headaches and I am sure we are not alone there.

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