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Old   November 2, 2011, 06:19
Default Imbalances
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I found out that uncontrolled big imbalances (continuity or momentum equations) may lead to physical instability and therefore for example to another flow regime (especially in multiphase flow-parallel computing).

Can anyone agree to that or tell me about such an experience.

Jessica
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Old   November 2, 2011, 21:55
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Yes, if a simulation is far from converged, or even worse diverging, the results could be anything. Including being in completely the wrong flow regime.
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Old   November 3, 2011, 03:19
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Yes i agree. Nevertheless for mass transfer or heat transfer it will be hard to stay under 1% for the conservation target...
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Old   November 3, 2011, 04:57
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Some simulations are hard to get the imbalances to converge. Often these are simulations with big variations in time scales - the short time scales are converged but the longer time scales take lots of iterations to converge.
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Old   November 3, 2011, 05:08
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yes in fact, the simulation will be expensive.
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Old   November 3, 2011, 06:22
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That's right. Simulations with a large range of any scale are difficult - length (very big sections going to very small sections), time (long and short time constants), or anything else.
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Old   November 3, 2011, 08:40
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It was irritating me the fact that even the support did not know or gin out the problem, it is clear that numerical imbalance lead to physical insatiability but i have not thought that it artifacts the results dramatically.

Now i am trying to build new accurate test case
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