Hello,

I have to analyse an enclosure with a heated wall. I'm using buoyancy, density is f(T,P).

The initial condition is T=293k and rho=1.205Kg/m3.

It is a steady state analysis.

The question is: during the analysis (reading .info file) the mass of the fluid and the average density (Mav and Vav) go down. What is wrong?

Thank you Gianni

If you are heating up yout computational domain, then it is normal that your density is changing (since density is getting lower when your temperature is rising) and decreasing, what would explain why the *average* density value and the *average* mass is going down. Have you checked that the total mass is conserved? This is the only important thing. If you have inlets and outlets, you need to include in your balance the mass entering and the mass leaving the computational domain. If your results are converged, everything should be balanced.

Thank you,

the problem is that the value of field total mass goes down with average density and there are no inlet or outlet boundaries!

If I try a transient analysis the field total mass is conserved.

What do you think about this?

Gianni

I had to give a conceptual design idea for simulation of a similar kind of model and I had inlet and outlet condition and also I used transient analysis rather than steady state analysis and it worked.

I guess you should go for transient analysis.

Xobile

Unfortunately the transient analysis is too much time expensive (some days).

Have I to set anything for total mass conservation in steady state analysis?

Gianni