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-   -   How to define the mass diffusion coefficients of species? (http://www.cfd-online.com/Forums/fluent-udf/63834-how-define-mass-diffusion-coefficients-species.html)

legendyxg April 21, 2009 10:37

How to define the mass diffusion coefficients of species?
 
My model is about the diffusion of multicomponents in porous media. I want to modify the mass diffusion coefficients including the effects of porosity and tuotorsity so I need to define the mass diffusion coefficients of each species separately, so how can I make it?

gemini May 10, 2009 16:29

Quote:

Originally Posted by legendyxg (Post 213675)
My model is about the diffusion of multicomponents in porous media. I want to modify the mass diffusion coefficients including the effects of porosity and tuotorsity so I need to define the mass diffusion coefficients of each species separately, so how can I make it?

Hi, I think you are modeling fuel cells. You can use define_diffusivity macro, in this way you can define only Dim (i.e, dffusivity of species i in mixture). Another issue in fuel cell electrodes, you cannot specify different porosity tortuosity correction for different directions. :(:mad::confused:

I am also working on modeling of fuel cells but I could not find a proper way to incorporate "full" multicomponent diffusion in porous electrodes in a fuel cell. Also, I could not solve direction dependent porosity corrections issue, yet.

good luck to you :cool:


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