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Acceptable %mass imbalance for turbomachinery

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Old   September 28, 2021, 03:58
Default Acceptable %mass imbalance for turbomachinery
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Mandar Patil
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I am running a steady state simulation for centrifugal compressor. The mass and momentum residuals have reached 10^-4 ,but there is about +5,-5% mass imbalance.Should I consider this as converged?
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Old   September 28, 2021, 07:07
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Glenn Horrocks
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Do a sensitivity analysis and find out if it is significant in your case. So do a another simulation where you converge much tighter and see if there is any difference to things of importance to you.
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Old   September 29, 2021, 08:40
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Originally Posted by mandar55patil View Post
I am running a steady state simulation for centrifugal compressor. The mass and momentum residuals have reached 10^-4 ,but there is about +5,-5% mass imbalance.Should I consider this as converged?
In general, the acceptable mass imbalance is 0. (machine round-off). Unless you are having severe convergence issues, the mass imbalances in ANSYS CFX are usually the lowest of all the equations.

Are you running a single-row compressor or a multi-row machine? Where is the mass disappearing? at the domain interfaces?
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