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Simplefoam and Delta t

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Old   January 10, 2006, 06:55
Default Hi everybody, I'd like to k
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Rosario Russo
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Hi everybody,

I'd like to know if it is possible to set the size of the timestep while using the stationary solver simplefoam.
I mean the numerical time step. I guess that the timestep can be different according to the cell size in stationary problems.

In some of my testcases I noticed that in small cells I have convergence problems and I'd like to control the timestep in these cells.

Have I to use icofoam even if I'm interested only in the stationary results?

Thank you for any suggestion.
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Old   January 12, 2006, 14:57
Default simpleFoam uses underrelaxatio
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Mattijs Janssens
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simpleFoam uses underrelaxation which is equivalent to local time stepping.

There is no control apart from changing the underrelaxation factor. Try using different discretisation. Or maybe your problem is transient.
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Old   January 13, 2006, 04:51
Default Just after posting my message
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Rosario Russo
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Just after posting my message I had a look at the code and I realized there was actually no local timestepping, but relaxation. I should have known that.
Sorry for my silly question.

Thank you very much for your answer anyway.

By the way I have another stupid question.

Is that possible that recompiling some solver (simpleFoam in this case) without any changing I get different (best in convergence) results? Or must I have missed something?

Thank you again.
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Old   January 13, 2006, 05:02
Default There might be very small diff
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There might be very small differences if you compile with/without optimization or on a different machine. We compile with -O3 -ffast-math on a p4.
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