EDC Combustion model small scale mass fraction
Hi,
I have a question about the eddy dissipation concept. The reaction rate of a specie i in fluent is defined by
Where ( )* denotes the small scale part. In the manual it is not documented how Y* is calculated and I'm not able to derive the Ansys formula from the original paper.
Best Answer

wcao Member Posts: 37
Hello,
The calculation of Y* is through time integration over the time scale tau* via either a stiff chemistry solver of chemkin CFD solver. Basically they are just ODE solvers that integrate the species mass fractions via the reaction rate calculated by Arrhenius law with temporary mass fractions. If you are referring to Magnussen for the original paper, most of the formula in it is assuming fast chemistry so that it might not be a good start point. You can refer to the article below, which has some derivation from Magnussen to the formula used by Fluent:
De, A., Oldenhof, E., Sathiah, P. and Roekaerts, D., 2011. Numerical simulation of delftjetinhotcoflow (djhc) flames using the eddy dissipation concept model for turbulence–chemistry interaction. Flow, Turbulence and Combustion, 87(4), pp.537567.
Answers
Hello,
The calculation of Y* is through time integration over the time scale tau* via either a stiff chemistry solver of chemkin CFD solver. Basically they are just ODE solvers that integrate the species mass fractions via the reaction rate calculated by Arrhenius law with temporary mass fractions. If you are referring to Magnussen for the original paper, most of the formula in it is assuming fast chemistry so that it might not be a good start point. You can refer to the article below, which has some derivation from Magnussen to the formula used by Fluent:
De, A., Oldenhof, E., Sathiah, P. and Roekaerts, D., 2011. Numerical simulation of delftjetinhotcoflow (djhc) flames using the eddy dissipation concept model for turbulence–chemistry interaction. Flow, Turbulence and Combustion, 87(4), pp.537567.
Hi wcao,
you just saved me a bunch of time. Thank you so much I would never find it on my own. Yes I meant the original paper from Magnussen. I will have a look to the posted paper!