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Adaptive Timestepping by using the acoustic Courant Number

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Old   February 3, 2020, 09:02
Post Adaptive Timestepping by using the acoustic Courant Number
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Patrick
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Hi,

i want to use the acoustic Courant Number for transient simulations, becuase i invastigate the sound propagation in pipes. I use the option adaptive time step with Max. Courant Number, but Ansys CFX uses the "normal Courant Number".

I read in the Ansys CFX Theory Guide, that it is also possible to use the acoustic Courant Number (1.1.3.15, page 22):
"The timestep may be chosen adaptively based on a Courant number condition (for example, to reach
RMS or Courant number of 5). The acoustic Courant number is used for compressible flow calculations
having the expert parameter setting ‘compressible timestepping = t’."
Unfortunaly, i can't find this option in the expert parameters.

Can anyone please help me? Or does anysone know how to use the acoustic Courant Number in transient simulations?

Greetings
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Old   February 3, 2020, 17:17
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That expert parameter might not be in the GUI but you can set it using the command interface.
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Old   February 3, 2020, 17:36
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Thank you! I never worked with the command interface before. How can i adress this parameter?



Is there any good Tutorial or something else which explains the use of the command interface?
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Old   February 3, 2020, 17:46
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The easiest way is to:
* Insert an expert parameter (any expert parameter, it does not matter which) using the GUI
* Right click on the expert parameter and select Edit in Command Editor
* Replace the expert parameter you just generated with the one you want to add.
* Click Process for it to process it and add it to the simulation.
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Old   February 9, 2020, 11:40
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Thanks, it works!
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acoustics, cfl number, courant number, time stepping

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