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Old   September 3, 2004, 10:02
Default Convergence Problem
  #1
Lu
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For impingement cooling case, I got good convergent result for continuity, momentum and energy equation.But flunctuation came out for k and epsilon. I tried to change the under-relax factors, the problem still remains. Give me some hints, thanks. btw, a ske turbulent model is applied for this case.
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Old   September 21, 2004, 07:06
Default Re: Convergence Problem
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hadi
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Hi; I have the same problem.But in my problem coolant do not impact to the Surface.I dont know what should i do. If you you know let me to know. thanks.
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Old   October 3, 2004, 08:48
Default Re: Convergence Problem
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ap
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Try to obtain convergence using the first order discretization scheme for turbulence quantities, the eventually switch to an higer one if you need more accurate results.

If you try to simulate in steady conditions and your case you can't obtain convergence. To do so, you need to switch to an unsteady calculation.

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ap
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Old   October 4, 2004, 03:02
Default Re: Convergence Problem
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venu gopal
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You can't decide convergence of a problem from the residuals alone. In some of the cases residual will not come down but the solution will converge as per the results concern. So, what you have to do naa, monitor a critical parameter of your problem ( for example avg. shear force in a particular plane or average velocity in a plane, or average temperature). Monitor this in one separate window. If possible you can monitor two critical parameters. If these critical parameter are becoming constant while iterating, then you can stop your solution and you can say that you solution converged. Residual plots alone will not dicide the convergence of a problem. Definitely it will work nicely.

Venu Gopal
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Old   October 12, 2004, 15:28
Default Re: Convergence Problem
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ap
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Yes, of course. But usually residuals reduction is one of the parameters to judge the convergence. Obviously it depends on the quality of the initial condition, so if you give a good initial solution, you may risk not to obtain a residual reduction big enough to satisfy your convergence criteria.

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ap

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