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Old   July 1, 2013, 05:35
Default continuity residual problem
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HI.

I am modeling channel with two inlet (water+air) with velocity inlet for inlets and pressure outlet for outlet boundary.
But in solving, i am trying for 2000 iteration and more but continuity residual does not cross down of continuity criteria ( 0.001) and solving is keeping and not stop.
Can you help me?
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Last edited by flow_CH; July 19, 2013 at 02:41.
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Old   July 19, 2013, 02:41
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please help
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Old   July 19, 2013, 06:24
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are you using any urf for density? Just set it to 1
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Old   July 19, 2013, 06:28
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No. I am not using urf.The density for air and water is constant.
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Old   July 22, 2013, 06:04
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You can try refining your mesh. Also increase the order of discretization.
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Old   July 22, 2013, 12:08
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It may be that there's absolutely nothing wrong with your simulation. The values of the residuals is scaled with the residuals at the start of the calculation. If your initial guess was particularly good then residuals won't drop so much but still you will have a physically valid result.

If residuals are stable for a long number of iterations and other physical parameters of interest in your simulation (in your case maybe the pressure drop across the pipe could be one) are stable too and the results do not show anything clearly wrong then I guess you can consider your simulation correct.
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Old   July 23, 2013, 02:46
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To gain insight if robbofleas statment applies to your case, you can switch your simulation to double precision. Then the residuals should drop further.
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