I have some problem with my result and I think that the mistake may be in my UDS. The equation is the following differential equation: �݃Ó/�Ýt=S. The source term may depend of temperature, pressure and ƒÓ. This equation is coupled with the continuity, momentum (x,y) and energy equations.

I calculated separetely �݃Ó/�Ýt and S and I saw that these two quantities is not equal. Fluent is supposed to solve the UDS equation at the end of a time step after the momentum, continuity and energy equation. So I thought that there is may be a kind of numerical mistake like Fluent solve properly the four equations without the last one for the UDS.

I decided to simplify my problem and I decoupled my system of equations. I posed that my source term is a constant. In that case, the continuity, momentum and energy equations are coupled together and the UDS is alone (I wrote the transcient term to not be dependent of the density like in the documentation). I saw that �݃Ó/�Ýt and S were not equal too.

First of all, I think that the UDS variable may be coupled in the others equations. If it is the case, I didn't see anywhere the information in the documentation.

Actually, I really don't understand and it is probably a misunderstanding in the way to solve the entire problem.

I think that �݃Ó/�Ýt and S must be equal. What do you think about this fact? Could you send me any suggestions about this post? Salutation, David

Sorry for the bad character. Just replace the following equation: �݃Ó/�Ýt=S. by variation of density/variation of time = source term.

Salutation, David