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convergence in different boundary condition

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Old   September 1, 2004, 02:01
Default convergence in different boundary condition
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hello all

I have a problem with bad convergence. This model was well solved. But i changed the outlet mass flow rate, the model's convergence was bad. So i adjusted the physical timescale, still the residual is not satisfactory. Can somebody help me?. if you need more explaination, please e-mail me.

thanks in advance.

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Old   September 1, 2004, 02:51
Default Re: convergence in different boundary condition
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Try few of these:

1)solve for laminar flow, then use the solution as a start for turbulent cases.

2)start with a very small timescale and then during the iteration, increase the time scale

3)can you use 'openning' BC?

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Old   September 2, 2004, 13:04
Default Re: convergence in different boundary condition
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In addition to what HK said, you might

1.check that the mass is balanced. That correct mass flow is being specified at the outlet.

2.check different scheme too, thus either UPWIND or Blend and can then be changed to higher scheme!!

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