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Imbalance in transient simulation

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Old   December 8, 2009, 10:50
Default Imbalance in transient simulation
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Roland Rakos
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Hi,

While the calculation is running, I always check the mass/energy imbalance and the mass flow at the inlet/outlet.

In steady state simulation there is not problem with these, but I don't understand what does the mass imbalance mean in the case of transient simulation. End of every timestep the imbalance is under 0.1% but the mass flow at inlet and outlet are different (for example 0.3kg/s @inflow and 0.35 kg/s @outflow).
How is this possible?

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Roland.R
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Old   December 8, 2009, 12:05
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Old   December 8, 2009, 17:55
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Glenn Horrocks
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Assuming your imbalances are small, in a transient simulation it means your modelled domain is loosing mass. This can only happen in a compressible simulation. If it is happening in a incompressible simulation then you have a problem.
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Old   December 9, 2009, 06:39
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I thought so

Thank you;

Roland R.
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