[zkzkzk010537]

Can some please tell how to check Lewis number of each species for non-premixed combustion? (Even though it seems lewis is assumed as 1 but can we check it, or how will it affect result if my spicies are not having lewis=1)

Chmikin mechanism is imported and generate the PDF table!

Thank you !

ps: how to active User defined turbulent schmidt number?

[zkzkzk010537]

So, no one knows how to check lewis?

[zkzkzk010537]

And anyone knows how to use pope correction for round jet? with extra term describing vorticity? C-epsilon3=0.79?

[macfly]

Hi zkzk234304398532,

Regarding your initial question, the mixture fraction/pdf model is derived assuming Le = 1. In order to calculate the Le number, you would have to implement a udf that calculates local binary diffusion coefficients Dij function of temperature, then diffusion coefficients of species i in mixture Dim (the simplest method being the 1950 C.R. Wilke's approach...), and then the local Le number for species i...

You could start by assuming a constant diffusion coefficient for all species and see what Le numbers you get with the udf. Check some tables to see if the diffusion coefficients vary a lot with temperature, as temperature varies a lot in a combustion problem.

It's probably simpler to run your problem with the Eddy-Dissipation model and constant diffusion coefficients for all species, and just create custom field functions that calculate the Le number of each species. You could do the same thing in the mixture fraction/pdf model and enter a constant instead of selecting a species diffusion coefficient when you create the custom field functions... Then you would have a good idea if it's justified to go on the journey of implementing a udf for the mixture fraction/pdf model...

Hope my explanations are clear... 1st langage is french...

[zkzkzk010537]

Thanks for your reply, i will try that on monday