Hi Yacine,

The local equivalence ratio is defined on the basis of the local mixture fraction value, so you have to initialise your case with a non-uniform mixture fraction distribution. You can do this in two ways: the first one is to patch different mixture fraction values (corresponding to the different desired fuel/oxidizer ratio values) in your domain, the second one is to use the DEFINE_INIT udf macro to initialise your case.

Andrea

Hi, yacine

You can patch  desired  concentrations in the domain of your interest. but I'm not sure whether it will  be as it is  with time elapse.

Thanks', but how about the calculation of the PDF Probability Density Function of the mixure, will it take into account this non-uniform concentration?

Yes the PDF integrals are pre-calculated and stored in the PDF table, so in each cell Fluent will retrieve the favre-averaged scalar quantities from the table based on the local values of the mixture fraction and its variance (and of the progress variable and its variance values as well if you are using the partially premixed model)