how to use UDS
 

Dear ,
i work on the solidification of water+salt alloy...when the freezing begin we will have a pure phase of ice+ a melt rich in salt..i must model this with fluent...with solidification/melting model tha species transport is not allowed, so to include the mass transport of the salt from the ice to the liquid, i have to use define UDS...
my questions are, how many uds have i to put?? and with wich values??
in general, how to use UDS to model the solute transport..
thanks..

help please:confused: