# steady state solution

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 July 9, 2007, 09:13 steady state solution #1 cfxdude Guest   Posts: n/a Hi, Does steady state solution depends on your initial guess? cfxdude

 July 9, 2007, 09:35 Re: steady state solution #2 Gert-Jan Guest   Posts: n/a 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

 July 9, 2007, 09:57 Re: steady state solution #3 cfxdude Guest   Posts: n/a 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

 July 9, 2007, 10:31 Re: steady state solution #4 Gert-Jan Guest   Posts: n/a When your monitoring values are fluctuating, you won't have a steady state situation. Looks like your problem is time dependent. Gert-Jan

 July 9, 2007, 10:38 Re: steady state solution #5 cfxdude Guest   Posts: n/a 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.

 July 9, 2007, 18:20 Re: steady state solution #6 Glenn Horrocks Guest   Posts: n/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

 July 9, 2007, 18:28 Re: steady state solution #7 Italy Guest   Posts: n/a 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

 July 10, 2007, 05:43 Re: steady state solution #8 Helge Guest   Posts: n/a 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

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