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Conjugate heat transfer and reactingFoam (chtMultiRegionReactingFoam)

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Old   October 15, 2023, 13:05
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Domenico Lahaye
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Eric makes a good point. The reverseBurner test case might be good to look into. Our documentation on reserveBurner is at https://mega.nz/file/eBcxWKgJ#CXhpWd...5O3CHRBqIX6XKk

Good luck.
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Old   October 16, 2023, 06:35
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Hey!



Regarding radiation in the solid, I don't think the solver can handle a participating solid, meaning that there is no radiative field solved in a solid region (I may be mistaken, please correct me if that is the case). So the absorptivity does not matter for a solid region when using the opaqueSolid model.


Having the option to model a solid as a semi-transparent medium would be a great feature to have for CHT applications, but I don't think it is (yet?) implemented
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Old   October 16, 2023, 13:23
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Domenico Lahaye
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What happens is case of switching on the radiation in the solid?

Solid and fluid have distinct settings for density rho, heat capacity Cp and thermal conductivity k.

If radiation does work for fluid, when not for solid? Is this a case of radiation submodes not (yet) being implemented?

Cheers, Domenico.
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Old   October 16, 2023, 16:38
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Solver-wise, I am not sure what happens, I never took the time to look at the code properly. But there is no radiative field written for solid regions even with the radiation switched on.


My guess is that you have to turn it on to indicate that you expect radiation to happen in the fluid regions, and maybe to use certain boundary conditions such as turbulentTemperatureRadCoupledMixed that refer to neighbouring fluid regions and their associated radiative field. The heat transfer at the interface between the solid and the fluid takes into account the radiation coming from the fluid, but there is only conduction on the solid side.


Quote:
If radiation does work for fluid, when not for solid? Is this a case of radiation submodes not (yet) being implemented?
I am not experienced enough to know where the differences lie and what it would take to implement radiation in a solid or semitransparent medium Maybe it is really simple and just a matter of not being requested by the userbase.


One trick I have seen and tried myself is to model a solid region as a frozen fluid that still allows radiation to be solved. But one of the main issues is that the rays (if you use fvDOM) are not propagated through the interface between two fluid regions. The radiation is solved separately for each region, if that makes sense. And there is no boundary condition for internal transparent walls or baffles as far as I know.
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Old   October 16, 2023, 16:54
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Eric Daymo
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Hi Domenico and Alczem,

Thanks for the replies and the helpful discussion.

Going back to sante_junior's original question, he wished to know if absorptivity of zero mean that " refractory wall doesn't absorb any energy." If the turbulentTemperatureRadCoupledMixed (now called coupledTemperature in OF 11) BC is used, radiative heat from the fluid side can be transferred to the solid, even if absorptivity is zero. This is consistent with Alczem's reply, I think.

I believe Alczem is correct that there is no radiative field solved for in the solid. I think this is supported by the comments in the opaqueSolid file in OpenFOAM: https://github.com/OpenFOAM/OpenFOAM.../opaqueSolid.H ... i.e., there is no source term generated for radiation with the opaqueSolid model.

With respect to whether absorptivity and emissivity fields do anything at all in the solid phase, I am not sure. The reverseBurner tutorial, for example, sets an emissivity of 0.1 on the solid side.

Domenico, if I understand the reverseBurner document correctly, you explored the fluid-side absorptionEmission properties, but not the solid side?

The other thing I am now not sure if is if the radiative heat is transferred from the fluid to solid side via the boundary condition, can radiative heat transfer to the solid side if the solid radiationModel is set to 'none'?

Thanks for exploring these matters together.

Best regards,
Eric
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