Hi!

I´m a beginner in UDF´s. I´d like to create one UDF to simulate a methane combustion (CH4 + 2O2-->CO2 + 2H2O).

The reaction mechanism is (-R_CH4)=k1*YCH4^0.72*e(k2/T)[mol/s·m3] where K1 and K2 are constants, T is temperature and YCH4 is the molar fraction of methane.

can anybody help me?

thank you

You probably already realize that UDFs are quite time consuming - especially if you are just getting started.

Why don't use just use the framework already built in to Fluent to do an Arrhenius rate reaction with the species transport equation?

I tried it.

First of all, I simulated de methane combustion with the reaction mechanism that FLUENT supplies.(with the Arrhenius parameters). Then, with this outputs I tried to simulate the reaction "on my own" deselecting the reaction option in boundary conditions and selecting the sources option. Results were similar, but now I have to solve the combustion with that chemical kinetic equation and it seems that UDF´s are neccesary...What do you think?

Thanks for your time.

You should use the UDF macro DEFINE_VR_RATE( name,c,t,r,mw,yi,rr,rr_t). Follow the example in the UDF manual, it's not very complicated.