UDS-diffusivity

chinli

Dear All,

I am asked to use UDF and UDS in my project.To start off with the very basics, I am asked only (for the time being)to set Diffusivity coefficient of air=1

I could not remember exactly what I did, but roughly it goes like this:

Under Define/User-Defined/Scalars, I put number of user defined scalar as =1 and flux function none

Then under the materials panel of air, i have this additional scalar UDS diffusivity and when I click on edit the UDS diffusivity coeff panel pops up and there is a whole list of uds-0, uds-1 etc which also appears in the manuals.

I guess the number under the coefficient will be the number of diffusivity coeff I want air to be.

However I am confused by the procedures. WHat if I am asked to introduce a scalar tat is not diffusivity but something else, should i under Define/User-Defined/Scalars, I put number of user defined scalar as =2? since if i put 1, diffusivity is shown on the materials panel.

And what is the meaning of the uds-0, uds-1, uds-2 etc shown on the UDS diffusivity coeff panel means? Why are there a whole list?and not just a panel that contains just

"Diffusivity Coefficient= 1"

I am really confused and are doing things that I don't even sure what am I doing. Hope can hear some opinions from anyone.