Evaluation of heat fluxes (conduction & radiation)

[arved]

Dear Peter, dear Elmer community,

I am working on 2D axi-symmetric simulations including both heat conduction and radiation. Unfortunately, I have some issues with the evaluation of the heat fluxes over the boundaries:

- In a verification setup with two concentric spheres (radiation only) the Boundary Sum over Temperature Loads gives me wrong heat fluxes (2D axi-symmetric), while it gives the right results in 3D. Is there anything wrong with my inputs or may this be caused by my 2D setup?

- In the complete simulation (both radiation and conduction) I have troubles getting a total sum of zero evaluating all boundaries of one body using the FluxSolver / SaveScalars / diffusive flux (same as in the sphere example). May this be due to the discontinuity of the fluxes caused by the radiation? If yes: Is there any other evaluation routine that I can use?

I am using the Solver Version 8.4 (Rev: Release, Compiled: 2020-04-09).

Thanks in advance for your help!

Best regards
Arved

[raback]

Hi

Would multiplying with 2*PI help? Weighting with the 2*PI*r is needed in axially symmetric cases and often the 2*PI is dropped which means that resulting reaction loads also are too small by the same factor.

-Peter

[arved]

Yes, that helps, thank you! The temperature loads * 2 Pi are equal to the heat source, which is the result I expected.

Do you have any suggestion for the evaluation of heat fluxes at boundaries with both heat conduction and radiation (my second question)?
If not I'll have to evaluate the contribution of the conduction to the total heat flux at a slightly shifted position, which however would make my setup more complicated.

Best regards
Arved

[raback]

You might have flux solver active only on the one side. Certainly radiation is not treated by the FluxSolver and the flux will not be continuous over interfaces resulting to unexpected features. -Peter