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Old   December 20, 2007, 07:13
Default Divergence
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I encountred a problem of divergence with continuity, and velocity residuals, especially when I put a large number of iteration per time step. How can I solve to that? Thanks.
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Old   December 27, 2007, 21:04
Default Re: Divergence
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What is the problem you are trying to solve? what are ur Bcs, under-relaxation factors?
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Old   December 28, 2007, 05:42
Default Re: Divergence
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I encountred a problem of divergence with continuity and velocity residuals, especially when I put a large number of iterations per time step (>=10). I should mention that this doesn't happen if small number of iteration is put. (1-5).

Even,I lowed the under relaxation factors of pressure (0.3-0.4), momentum (0.4)! Or changed the initial velocities, or turned off the energy equation for first iterations, in vain!

it gives this error message: Error: divergence detected in AMG solver: vof-1 and then: Error: floating point error: overflow Error Object: ()

What do you think, what can be the cause?

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Old   January 1, 2008, 04:48
Default Re: Divergence
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Hi Safa, From what you have given here, it looks like you are trying to solve a multiphase problem. VOF-Liquid may suddenly shot up to a value that could have led to the divergence. There is no easy answer to this except continually experimenting with the URFs. With regard to the no. of iterations, is ur problem converging in each time-step when you reduce the no of iterations per time-step?
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