Dear, all may be anybody could know the reason..

I have set that the density of the fluid is temperature dependant. My thermal/cfd calculation solutions seems quite physical,as well as Max residuals seems fine. In the same time P-Mass imbalance (imbalance of equation) is jumping streight from -1 to 1 and back - each iteration.

If I set a constant density - P-Mass imbalance is 0.

Is it OK with the values 1 and -1 (it is recomended 0.01 default value for conservation target)?

Do you have a closed system? The individual contributions to the imbalance may then all be close to zero and the +1/-1 switching due to the fact that there is nothing meaningful available to normalize an imbalance which is actually roundoff.

Yes, my system is closed. Did I understand correctly - everything is fine because the value, which is normalised is not important because very small. If so - thank you