User defined materials

Is it possible to enter user defined materials?

I must simulate CO2 surface adsorption onto porous media sites, and my current idea is to create some solid material ‘CO2*’ to model an adsorption site.

Having trouble finding anything relevant to this in the user guide.

You can define the gas phase and solid phase as, CO2g and CO2s.
Define the chemical expression as
Add the reaction heat.
And copy the thermal data of CO2 twice, change their name into CO2g and CO2s.
Define the reaction rates in usr_rates_des.f if discrete methods (DEM or PIC) are used, or usr_rates.f if TFM is used.

That advice sound pretty intuitive, actually. Thanks, will definitely give it a shot.

I’ve been thinking about this more - haven’t actually tried it - but the surface reaction I’m trying to model is such that the CO2 doesn’t actually form a solid, it remains as a gas when captured in the adsorption sites.

I’m inclined to use CO2(s), ‘s’ as in ‘site’, a reaction with CO2(g) would be similar to the following:

CO2(g) + CO2(s) ->CO2(gs)

Where (g) is gas (s) is site, and (gs) is a filled site. My conceptual issue with regard to how MFiX performs reactions is that I’m unsure how to create CO2(s) and CO2(gs) and get MFiX to accept it.
It seems as though you’re telling me to do exactly that, but without mention of CO2(gs). It’s important because there’s a finite number of CO2(s) in the domain. So do I model CO2(s)/CO2(gs) as an internal value, or do I have to explicitly model them as “materials” (fluid or solid)?

Thanks so far!