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Old   August 24, 2014, 02:03
Question Appropriate time step
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Henry Arrigo
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Hi all,
How is it possible to calculate overall mean value of convective Courant number with a given time step. I want to set the overall mean value of convective courant number around 1, but I don t know how to choose the appropriate time step.

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Old   August 24, 2014, 08:45
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Ping
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create report ot type mean for cfl then use this in a field function formula calculate the required timestep and use this as the timestep

however this is maybe not a good idea depending on your flow since an important area of the flow might have cfl much higher than one and so is being poorly modelled
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Old   August 25, 2014, 04:44
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thanks ping,
would you give me an example of what you name "an important are"?
and, based on what you said it must be more rational to use maximum CFL report instead of the average, rights?
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Old   August 25, 2014, 05:59
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an important area is somewhere where capturing the flow accurately is important ie there are areas in most cases where it is less important to have a fine mesh or a reasonable cfl number

yes based on max cfl is much safer but could be too conservative if some spurous cells have large values for a silly reason
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