Hi,

Does steady state solution depends on your initial guess?

cfxdude

A complete converged solution (i.e. constant values in monitoring points, imbalances=0, RMS residuals < 1e-6) should not depend on initial guess.

Gert-Jan

Hi,

What you are saying is that If 1e-5 < RMS residuals (pressure and velocities) <1e-4 and 1e-6 < RMS residual (k-e turb) < 1e-3 is not a steady state solution, or the solution depends on the initial guess?

In my case the velocity of the monitored point is fluctuating between 0.25 - 0.35 m/s (11000 iteration), but the volume average velocity is constant. which one is the correct steady state indication.

Thanks.

cfxdude

When your monitoring values are fluctuating, you won't have a steady state situation. Looks like your problem is time dependent.

Gert-Jan

So constant volume average velocity is not the steady state indication.

Is there any book or paper about these, I am looking for some thing written.

Thanks for your time.

A.A.

Hi,

For a small number of situations the steady state solution does depend on the initial guess. I have seen some flows were the Coanda effect caused a jet to stick to one wall or the other depending, then settle down to a steady state solution. Which wall the jet stuck to depended on the initial guess.

In general, however, a fully converged solution is independent of initial guess.

Glenn Horrocks

If the velocity of the monitored point is fluctuating between 0.25 - 0.35 m/s after 11000 iteration, try to increase gradually the timescale. In this way you should obtain a non fluctuating velocity value.

Probably now you are reading some fluctuations of your domain; increasing the timescale works as a filter for this numerical fluctuations.

Bye

Alberto

Numerical fluctuations? You may damp out physical fluctuations by numerics. If you increase the time step you may stabilize the solution but you will not get a fully converged (grid independant and time step independant) solution.

I agree with Gert-Jan and Glenn