[Stabum]

Hello,
I have read some previous posts regarding the different meaning between residuals and imbalance. But there's something I still don't understand.
I've ran 2 different steady state simulations.
- The first one has converged very well (meaning that the RMS residuals have reached 1E-6 and MAX residuals have reached 1E-4 | 1E-5). When looking at the imbalance plots, on the contrary, I see wide "fluctations" in almost all the domains.
- The second simulation seems has not conveged at all (RMS residuals fluctating around 1E-4, MAX residuals fluctating around 5E-2). But looking at the imbalance plots, I don't see any fluctation (apart in one domain, which is in my opinion the most problematic one, from a geometric a fluid dynamic point of view).

I don't understand how I have to interpret the "apparent" convergence of the first simulation.

Is there someone who can help me??? Thanks in advance

[ghorrocks]

Residuals is how well the equations are solved in that control volume. Imbalance is how the sum of stuff in minus stuff out equates to zero over the whole domain. So Residuals is a form of control volume scale convergence and imbalance is a form of global scale convergence. There are other convergence criteria, these are just the most common ones in CFX.

Your first simulation simply has the equations solved quite well at the control volume level but when you look at global conservation it is not good. If global conservation is important that means this simulation is not well converged. If global conservation is not important then this result is probably fine.

[Stabum]

Clear as always, Glenn! Thanks, thanks so much!