|March 13, 2013, 19:46||
Understanding pimpleFoam convergence criterion
Join Date: Aug 2012
Blog Entries: 1Rep Power: 5
Hi, I have a question about convergence criteria for pimpleFoam. I read other relevant threads but couldn't find a clear answer.
My understanding is that with the simpleFoam solver, it is necessary to run until the 'p' residuals drop at least three orders of magnitude (1e-3) and the 'U' (Ux, Uy, & Uz) residuals drop about four to six orders of magnitude (1e-4 - 1e-6), then stop changing.
I'm now using pimpleFoam to obtain a transient solution (different boundary conditions). My understanding is that in this case, both the 'p' and 'U' residuals must drop around one order of magnitude per time step.
1) Should the initial residuals drop below a certain threshold before the transient solution is considered accurate? I saw in other threads that this was mentioned, but I saw no discussion on how this criterion is determined. If this is true, are pimpleFoam solutions always wrong during start-up? I don't really understand this.
2) How do you determine the criterion for how much the residuals should drop per time step?
Thank you community!
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