# SIMPLE BCs for flow in parallel plates

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September 21, 2015, 08:22
Residuals vs convergence
#21
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So i've implemented residuals (rms residuals) and also convergence between two iterations (rms convergence). I get oscillating residuals but all below 1e-5 whereas my convergence is monotonically decreasing. The velocity profiles predicted look okay. So which should i use as my stopping criteria, the residuals or the convergence?
Attached Files
 residuals and convergence.txt (634 Bytes, 2 views)

September 21, 2015, 08:53
#22
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Filippo Maria Denaro
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Quote:
 Originally Posted by kabz So i've implemented residuals (rms residuals) and also convergence between two iterations (rms convergence). I get oscillating residuals but all below 1e-5 whereas my convergence is monotonically decreasing. The velocity profiles predicted look okay. So which should i use as my stopping criteria, the residuals or the convergence?
difference bewteen two iterations is not meaningful for the real convergence

September 21, 2015, 09:03
#23
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Quote:
 Originally Posted by FMDenaro difference bewteen two iterations is not meaningful for the real convergence

Can I use both? If i was to rely on residuals alone, my algorithm would stop within 2 or 3 iterations (since they are always below 1e-5)

September 21, 2015, 10:31
#24
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Filippo Maria Denaro
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Quote:
 Originally Posted by kabz Can I use both? If i was to rely on residuals alone, my algorithm would stop within 2 or 3 iterations (since they are always below 1e-5)
the residual must diminuish below such value

 Tags incompressible flow, parallel plates, simple