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-   -   mass diffusivity (http://www.cfd-online.com/Forums/fluent/41629-mass-diffusivity.html)

saghir July 7, 2006 10:27

mass diffusivity
 
hi

while running a FLUENT simulation i am getting the following message: warning check material properties : invalid (zero)diffusivity in each iteration. i use kinetic theory for mass diffusivity.

what would be the problem.

thanks in advance


Ryan July 10, 2006 13:19

Re: mass diffusivity
 
Hi Saghir,

I had that problem too. Read up on what kinetic theory actually does. Somehow the results of that are giving a result of zero for one of your materials. Try just guessing a value to see if the program runs that way...if it doesn't, then there's a different problem.

Cheers, Ryan

saghir July 17, 2006 07:01

Re: mass diffusivity
 
Hello,Thanks for your help the program runs that way with a constant value of diffusivity . I use kinetic theory method because I do not know a formula to calculate the humid air-water diffusivity.


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