Stefan-Boltzman boundary condition

About the development of the FEM module/workbench.

Moderator: bernd

Post Reply
ttyUSB0
Posts: 3
Joined: Sat Nov 10, 2018 2:29 pm

Stefan-Boltzman boundary condition

Post by ttyUSB0 »

Hello!

I am trying to calculate model, which irradiates heat, and can't find how to set Stefan-Boltzman boundary condition, e.g a*s*(T-Tamb)**4

Can anyone help me? Or nonlinear conditions can't be set in FreeCAD?
User avatar
NewJoker
Veteran
Posts: 3018
Joined: Sun Oct 11, 2020 7:49 pm

Re: Stefan-Boltzman boundary condition

Post by NewJoker »

It's not yet implemented in FreeCAD but CalculiX itself offers radiative heat flux boundary condition. The equation is q=ε*σ*(T^4-T_0^4) where ε is emissivity, σ is Stefan-Bolttzmann constant, T is body temperature and T_0 is environment temperature. It can be defined with *RADIATE keyword. But since it's not supported by FreeCAD FEM module, you would have to export the input file and add this keyword manually. Then run the analysis outside of FreeCAD and import the frd file for postprocessing in FreeCAD.

You can find the details in CalculiX documentation: http://www.dhondt.de/ccx_2.19.pdf
ttyUSB0
Posts: 3
Joined: Sat Nov 10, 2018 2:29 pm

Re: Stefan-Boltzman boundary condition

Post by ttyUSB0 »

Thank you very much!
Started to read the manual.... :)
Post Reply