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physical time scale && advection time

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Old   May 29, 2016, 23:04
Default physical time scale && advection time
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Hi,
I am simulating steady state flow over a hydrofoil, but it doesn't converge to error less than 1e-4. I have read alot about the effects of time scale on the convergence, but still do'nt know how I can choose an appropriate physical time scale based on the advection time (reported at the end of out file). I mean is there any relationship between these parameters?
thanks,
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Old   May 29, 2016, 23:32
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If you have no idea about the physical time scale for your problem, I think it's better to choose automatic time instead. it should be noted that sometimes bad mesh quality leads to high residuals and you cannot reduce them even by setting a very small timescale.
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Old   May 30, 2016, 00:38
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This FAQ covers it: http://www.cfd-online.com/Wiki/Ansys...gence_criteria

In your case as you have a free surface it is highly likely that a steady state result is not possible (or at least not easy) and you will have to run transient to get it to converge.
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