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-   -   Deffusion Coeff. (http://www.cfd-online.com/Forums/fluent/31147-deffusion-coeff.html)

yeewan March 26, 2003 19:35

Deffusion Coeff.
 
Hi everyone, Now i have a case where a gas will diffuse into a porous media. But before that, the diffusing gas will pass through a inlet pipe which donnot contain the porous media.

I am using the species transport model. So my question is, what diffusio coeffient should i use?? the diffusion coeff for gas-gas? or the Deff for the gas-solid?? Thanks,

Steven April 14, 2003 08:57

Re: Deffusion Coeff.
 
Hello,

In this case, you may want to use different diffusion coefficients for different regions.

Dg0:diffusivity of the gas

Dg,eff:effective diffusivity of the gas in porous region

Dg,eff=Dg0*(porosity)^(turtuosity)

I hope that answered your question.

Steven

yeewan April 14, 2003 20:55

Re: Deffusion Coeff.
 
Thanks steven.

yee wn April 15, 2003 04:29

Re: Deffusion Coeff.
 
The Do and Deff i knew already. but then stev, in fluent i think we only can input one D for one gas pair... am i right?? correct me if i am wrong. So how do i input two different D??

anythings helpfull will be appreciated. what do you thinks, stev.??

also, can anyone provide some references about gas-gas diffusion in porous media so that i can verify my simulation.

THANKS TYW


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