[solmaz aryafar]

Hello friends,

I need some help for writing a piece of my udf.

In one equation in my udf whose main task is computing the coagulation kernel of the population balance model add-on module of Fluent I need the concentration (mol/m3) of my two existing species in the reactor which are present in very low amounts, i.e. they are not main substances but they play an important role in the process. So I need to obtain them from the solver in every time step. Now it's 2 days that I'm searching and I don't find my answer. I want to know what macro I should use.
First I thoght I should use C_YI, but I guess this doesn't help me to get the mass fraction of species from the solver to use it in my calculations in udf. Do I have to use Pdf_XY or Pdf_Yi ? because as I read it seems that PDF tables are use in combustion applications, am I right?

I really appreciate any help or hint! It shouldn't be so complicated but I cannot find it.

Thanks in advance,
Solmaz Ariafar.