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initial residual and final residual

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Old   May 9, 2013, 04:16
Default initial residual and final residual
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Maosong Cheng
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Hi FOAMERs,
what is the definition of the initial residual and final residual, which can be used to decide convergence ?
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Old   May 15, 2013, 05:20
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Anne Gerdes
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The initial residual is evaluated based on the current values of the field before solving an equation for a particular field . The final residual is evaluated after the solution of the equation is performed.
The intial residual is more important to decide whether a computation converges, or not.
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Old   May 15, 2013, 08:23
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Timo K.
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Hi Anne,

can you give some rule of thumbs for values, which should be achieved for the initial/final residual and how many iterations should be used for pEqn per cycle e.g. for a transient simulation with a standard PCG solver.

Best Timo
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Old   May 15, 2013, 08:29
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Anne Gerdes
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Initial residual: e^-4 or e^-5 is a good result. Final residual has to be smaller (e^-8).
I cannot answer your 2nd question.
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