[herb]

I derived a 2D case from the tutorial buoyantCavity by changing boundary type of patch "frontAndBack" to "empty" and reducing grid to 1 in z-direction.

I set "endTime" to 10000 iterations

buoyantSimpleFoam stops after 3350 iterations:
log.buoyantSimpleFoam: "SIMPLE solution converged in 3350 iterations"

After the 3350 itartions heat transfer has not balanced to a sufficient degree and thus temerature ist still rising significantly.

What are recommended ways to prevent "buoyantSimpleFoam" from stopping after 3350 iterations?

[Pappelau]

Good Morning Herbert,
you have two ways to prevent stopping ,
1: Increase Residual stop criterium (as example from 1e-4 to 1e-8)

2: remove residual stop criterium completely and monitor the temperature until the profile converges(and stop the simulation manually after 10000 its)

[GerhardHolzinger]

The residuals "only" tell you how good or accurate the flow is being approximated by the simulation. This is independent whether your case has reached equilibrium. In a transient simulation, the flow will always change no matter how small the residuals are.

Thus, if you want to stop the simulation when your case has reached thermal equilibrium, you need to construct some criterion which describes exactly this: is the thermal equilibrium reached?


My first try would be to create a codedFunctionObject which describes this, and which writes a file if your condition for thermal equilibrium is met.
Then, you can use the stopAtFile functionObject to stop the simulation when it detects the existence of this special file.

[herb]

From steady-state solvers like buoyantSimpleFoam I would expect stabilization of results as a mandatory stop criterium.

Thank you for the "work-around" using a codingFunctionObject.

Is there good reason, why stabilization of results as stop criterium is not implemented by default in steady-state solvers?