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Time varying fixed value patch and averaging

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Old   December 8, 2006, 12:04
Default Hello, I have implemented a
Hannes Kröger
Join Date: Mar 2009
Location: Rostock, Germany
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I have implemented a new boundary condition which is similar to the existing "timeVaryingUniformFixedValue". It allows not only the specification of a uniform fixed value for several time instances but also of full boundary fields.

I have used this boundary type to prescribe a boundary velocity to the LES solver (oodles) which has a certain mean value and RMS. When I run the calculation everything is fine and seems to be working well.
The problem is with the results from the averaging procedure in the LES solver. I expected to get the same RMS value on the inlet patch as I had prescribed. But what I get is different. Especially the RMS of the patch-normal velocity is factor 2.5 to high. I cannot say something about the RMS in the internal field of the domain, but they may be ok.

I was wondering if there is an issue with my time interpolation and I checked, but it is all ok.
Furthermore, I have implemented the same averaging procedure (for Umean and R) as in oodles directly into my boundary condition class to average the boundary field without going through the fvPatchField-mechanism. Then I get the expected result!

What may be the reason for the different results? Does anyone have an idea?

Best regards, Hannes

Btw: if someone wants to have a look at the code, it can be found here:
silentdynamics GmbH -
open source CAE software solutions & support
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