Hi fundoos!!

is it possible to model diffusion of methane in air using FLUENT without any reaction.i want to know how the concentration of methane changes with time.plz help me how to model.

thanx,satya

Dear sir I have a problem with this title. If it's possible for you please send me your received responses. Very thanks for your attention to my request. With the best regards. Mahdi saniee nezhad

I believe you can use the Eddy Break Up (EBU) Model. Make sure that you'll not set any finite rate chemistry and set the A constant of the model to 0. Thus, you'll have no reaction in your domain. However you'll need to solve the heat transfer equation. If you're not interested in the energy fields perhaps you may use a multi-component model. I'm not a FLUENT user, but I believe that you can do it. Every commercial code has multi-component capabilities (I think).
Good luck, cfd guy

I don't think one should use a turbulent mixing model in a quiescent fluid. Just use the multi-component diffusion model using the right binary diffusion coefficients.