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IDProjectCategoryView StatusLast Update
0001289OpenFOAMBugpublic2020-11-26 21:50
Reporterchriss85 Assigned Tohenry  
PrioritynormalSeverityfeatureReproducibilityalways
Status closedResolutionsuspended 
Summary0001289: Limited validity range for multi-band fvDOM model
DescriptionThe fvDOM model uses a blackBodyEmission class, which contains some pre-calculated values in a table for evaluating the integral over the planck function efficiently. However, the spectral range of this table is limited and doesn't cover some physically relevant ranges that can be appear (namely, in plasmas with temperatures between 2.000 - 50.000 K). In other works I've seen radiation being modelled between 30 nm and 4.5µm.

The table provides values for ranges of lambda*T*1e6 between 1000 and 50000.

In plasma applications values between 3e-8*2000*1e6=60 and 4,5e-6*50000*1e6=225000 can appear, for which this table is not sufficient on both sides (though the longer wavelengths contain not so much energy).

Instead, I propose to calculate these values on startup instead of using a predefined table. This way, they could directly be calculated, considering the used spectral range and a user-specified temperature range for generating reasonable sampling points in the table. It should not take too much time to evaluate the integrals I think.


I have another, slightly off-topic question: What exactly are the iEhrrCoeffs_ in the wideBandTabularAbsorptionEmission model?

The comment says: //- Proportion of the heat released rate emitted

I'm trying to implement a multi-band P1 model, and I don't see this coefficient appearing anywhere in my literature. Is it only relevant for fvDOM?
TagsNo tags attached.

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chriss85

2014-05-12 13:33

reporter   ~0003053

Alternatively, the user could provide a temperature-dependent table for each band containing the evaluated integrals. It would be nice to provide a script/program with OpenFOAM to calculate these tables then.

I will probably use this approach myself until a bigger range is officially supported.

henry

2020-11-23 12:22

manager   ~0011739

> Instead, I propose to calculate these values on startup instead of using a predefined table.

Can you provide an implementation?

henry

2020-11-26 21:50

manager   ~0011773

Pending funding or contribution.

Issue History

Date Modified Username Field Change
2014-05-12 13:29 chriss85 New Issue
2014-05-12 13:33 chriss85 Note Added: 0003053
2020-11-23 12:22 henry Note Added: 0011739
2020-11-26 21:50 henry Assigned To => henry
2020-11-26 21:50 henry Status new => closed
2020-11-26 21:50 henry Resolution open => suspended
2020-11-26 21:50 henry Note Added: 0011773