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-   -   UDS-diffusivity coefficient (https://www.cfd-online.com/Forums/fluent/78220-uds-diffusivity-coefficient.html)

UDS_rambler July 15, 2010 11:42

UDS-diffusivity coefficient
 
hello everybody! I'm trying to use a UDS model to describe the diffusion of species dissolved in a solution. I got the diffusivity coefficients I need in m^2/s but I can't understand whether using m^2/s as units for diffusivity is right, while next to the box in the drop-down list in materials properties the units are kg/m-s like viscosity. I thought I have to convert the diffusivity value in m^2/s, as Fickian diffusivity value for my species, to these units but it's a kind of freakingly strange thing I hope you can help me and i thank you as well!

chaozhong.qin July 15, 2010 16:29

Hi,

You have two different parameters of dynamic viscosity and species diffusivity. No change is needed.

UDS_rambler July 15, 2010 16:48

thank you for your prompt response!! So you mean I can simply use m^2/s as units, don't you? Because the theoretical formulation used in the user's guide confirms this fact, but the units you can find within the material panel for the diffusivity puzzled me!!...... thanks again for your attention!! :)

chaozhong.qin July 15, 2010 16:53

Hi,

I think so,


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