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

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

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.