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flow_CH July 1, 2013 05:35

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?
please see attached image

flow_CH July 19, 2013 02:41

please help

ishanv July 19, 2013 06:24

are you using any urf for density? Just set it to 1

flow_CH July 19, 2013 06:28

No. I am not using urf.The density for air and water is constant.

vasava July 22, 2013 06:04

You can try refining your mesh. Also increase the order of discretization.

robboflea July 22, 2013 12:08

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.

flotus1 July 23, 2013 02:46

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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