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Old   December 19, 2007, 10:16
Default Average Scale Information
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Christian Andersen
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Hi everyone, Im doing an transient calculation of a seal in a turbomachine with a rotating rotor in 3D. Also, the rotor is perturbated with a fraction of the rotational frequency.

I've done a sensitivity analysis on the time stepping and looked into the CFX manual. But can anyone tell me how the solver calculates the: "Average Scale Information " ??

Because, I would like to know if the Advection time scale is of any use to me in this regard.

The advection time scale is very similar and independent of my chosen time steps with a value of approx 8.4E-4, and my time step is 29E-6.

Thank you very much

Christian, Denmark
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Old   December 19, 2007, 12:14
Default Re: Average Scale Information
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Johnson
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Hi Christian,

the Advection Time Scale is simply the Average Length Scale divided by the Average Velocity Scale. It is designed to give an indication of the average timescale in the domain (e.g. from inlet to outlet), which can be useful in determining an appropriate timestep to use for steady-state calculations (usually a fraction of this quantity).

If the flow doesn't change significantly between your simulations, then this is likely the reason they are similar.

Regards,

Johnson
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