chem_2019-09-23T174108.609499.zip (201.7 KB)
I am using MFix-19.2, DEM model
I want to add one gas equation: CH4+H20–>CO+3*H2
Every time I add a chemical reaction, it will definitely diverge.
The residual of p is huge when it is about 400 iterations.
What is most weired is even when I removed the reacion and rebuild the solver, the same erro still happens.
So it does not converge without the chemical reaction? Make sure the model runs to completion without reactions before adding another layer of complexity.
thank you for replying.
It run smoothly when I don’t add any reaction. But when I add one reaction, it will diverge even if I removed the reaction.
It seems only when close all the program(I use the windows version), the diverging error stops.
Now I am curious what should I do to keep it from crashing for a “DEM with reaction case”. (someone told me to refine the mesh, is he right?)
By now, I didn’t find any tutorials case that satisfies “DEM with reactions”
Best regards
Since you are adding only gas phase reactions (no particles involved), it might because the chemical reaction rate is too fast, that made the fluid solver diverged. Try reduce the reaction rates first (*0.000001) manually.
If you want to model DEM solid reaction, try /legacy_test/dem-test/evaporation
Please turn on “Enable species equations” for the Carbon solids phase (Solids>Material pane). There is a little quirk when species are defined and species equations are not solved that prevents the Cp from being calculated. I think you may also need to define the thermal conductivities for each solids phase if conduction is not negligible.
thank you for your suggestions! I will try as soon as possible
I have a question: what do the solid species equations represent? If the fluid species equations represent “the diffusion of one species from dense to sparse”, does it mean the same thing for solids?
However I cannot imagine why the solid material can diffuse like the fluid phase. So I turned off the species equations of solids.
Maybe you are right, I will give it a try.
Thank you for your replying.
For DEM, the species equations are mass balance equations for individual solids species. You could have the conversion of one species into another, or interphase mass transfer that causes the mass to decrease/increate of individual species.
thank you for your explanation.
Now it stops diverge when I turned on the species equation.
