Hello, developers.

Suppose a set of electric filaments are placed close to the outer wall surface to heat a fluidized bed reactor with a power of 1000 W as shown in Figure.

How should we set the wall boundaries in dem? In the gas phase, using constant flux, specifically 1000/0.026 (0.026 is the thermal conductivity value of the gas), and in the solid phase, continuing to use an adiabatic wall?

Looking forward to your guidance, thanks.

I think you need to divide by the area of the BC plane. If Q=1000W=k.A.(dT/dn), then dT/dn=Q/(k.A).

OK, it’s very helpful, thanks.

In addtional, a study which I browsed before reported that the constant wall flux boundary condition in cfd-dem was immature and the model needed to be improved. They give a modifier formulas(please see Eq.28). May I ask if this is the case? Their correction formula is not complicated, but I can’t figure out how to find the corresponding source codes in MFiX and modify them.

A method to deal with constant wall flux boundary condition in a fluidized bed by CFD-DEM - ScienceDirect

You may want to contact the authors of the paper and see if they are willing to share the code with you.

Thank you very much for your reply! However, I’d like to confirm: are the existing constant wall flux boundary condition in MFiX currently mature enough to satisfy regular computational requirements, right?

This is a relative concept. The constant heat flux in MFiX-DEM only applies to the gas phase. It applies to gas and solids phases with TFM. If you need to run DEM with constant heat flux for the solids phase, you will need to implement one of the proposed models in the paper or develop a new one.

OK, I understand, thanks!