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High %SD-Sur Values @ I-Radiation Full Spectrum

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Old   June 24, 2016, 10:05
Default High %SD-Sur Values @ I-Radiation Full Spectrum
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Hey Folks,

I am doing a simulation of an solar-absorber, which seems to calculate very well. But I have problems with very high %SD-Sur values in th I-Radiation Full Spectrum (as u can see in the pictures), and I don't really have a clue how to fix it. The values fluctuate from 59% up to 100%.
My Model is very simple. Just a pipe with solar radiation from the outside.
So I hope somebody of you have any hints to lower that %SD-Sur values.

thanks an best regards

volleyHC
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Old   June 24, 2016, 10:31
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One question, how many histories are you using ? How much does the SD% changes, if you increase the number of histories by a factor of say 10?

Also, you can plot the Wall Irradiation Heat Flux.Normalized Std Deviation on the boundaries of your domain. On such plot, you may find the areas where the standard deviation is high, and decide if the sampling in that region is critical for your simulation.
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Old   June 24, 2016, 11:22
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I am doing 2,500,000 Histories at the moment. I did 1,000,000 before, but it didnt chang very much. I could try 10,000,000 but that would increase my calculation time too much I guess - but mabye it's the only way.

I looked up the Heat Flux.Normalized Std Deviation . And it looks like this:

Wall_Irradiation Flux_normStdDev_laengs.png

Wall_Irradiation Flux_normStdDev_quer.png

Well, I just refined my mesh very much, start my calculation again and got this message:
Code:
 +--------------------------------------------------------------------+
 |                     ****** Notice ******                           |
 |  Spectral band contribution to the spectrum is negligible          |
 |  Domain       : Default Domain                                     |
 |  Spectral Band: Vis                                                |
 |  Contribution :  0.60135-153                                       |
 +--------------------------------------------------------------------+
 +--------------------------------------------------------------------+
 |                     ****** Notice ******                           |
 |  Spectral band contribution to the spectrum is negligible          |
 |  Domain       : Default Domain                                     |
 |  Spectral Band: UV                                                 |
 |  Contribution :  0.60135-153                                       |
 +--------------------------------------------------------------------+
 +--------------------------------------------------------------------+
 |                     ****** Notice ******                           |
 |  Spectral band contribution to the spectrum is negligible          |
 |  Domain       : Default Domain                                     |
 |  Spectral Band: NIR                                                |
 |  Contribution :  0.60135-153                                       |
 +--------------------------------------------------------------------+
Is that anything to worry about, or just an information?

Last edited by volleyHC; June 25, 2016 at 04:49.
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Old   July 24, 2016, 13:03
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Does anyone has some hints/clues for me, to fix that problem?
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