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Old   July 23, 2007, 12:32
Default Hi, I want to know what is
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lam
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Hoang-Lam
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Hi,

I want to know what is the criterium of convergence for a solver in Fluent which solves something like simpleFoam (incompressible flow).
Because I want to compare Fluent's criterium and my criterium that I used in simpleFoam.

Thanks in advance,

Lam

p.s: and can Fluent accept a model viscosity like BirdCarreau?
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Old   July 23, 2007, 12:47
Default The standard convergence crite
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Alberto Passalacqua
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The standard convergence criteria adopted in FLUENT require that all residuals drop under 10^-3.

In my experience this requirement is not always satisfactory, especially for steady calculations. Usually I just set very low or zero residuals and check when residuals flatten and double-check convergence monitoring some property of the flow.

Yes, that viscosity model should already be implemented in FLUENT.

Regards,
A.
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Old   July 24, 2007, 05:00
Default Hi Alberto, Thanks for repl
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Hi Alberto,

Thanks for replying me.

Do you think that a criterium which is somthing like:
norm[U_(n+1) - U_(n)]/norm[U_(n)] < tol
is wrong for a steady computations?
Otherwise, why this criterium is not implemented?
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Old   July 24, 2007, 07:41
Default The residuals in FLUENT are de
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The residuals in FLUENT are defined as the errors of the discretized equations, i.e., a_P*U_P -{Sum (a_NB*U_NB) + S_U} i the case of U-momentum equation. They are often normalized (or scaled) by the factors of users' choice such as Sum(a_P*U_P}. I guess OPneFOAM uses the same definition.
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