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Old   July 3, 2015, 06:17
Default SAS unphysical wiggles
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Jose
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Dear all,

I am running a simulation of the flow around a bluff body. I am using the SAS-SST k-w turbulence model.

In the report below from ANSYS and in many other papers, it is recommended to use a discretisation scheme for the momentum with low numerical dissipation: Central Difference (CD) or Bounded Central Difference (BCD).

http://www.ansys.com/staticassets/AN...ing-models.pdf

BCD is more stable and should be the preferable option. However, when there is a unphysical delay in the formation of eddies, it is recommended to use the even less dissipative CD (this is my case). As CD is less stable, it can produce unphysical wiggles and in theory you should always monitor the solution to ensure that wiggles are not dominating the solution.

Here comes my question. I am using the CD scheme for the momentum discretisation, how can I differentiate the physical eddies with the unphysical wiggles? Or, how can I determine if the wiggles are dominating the solutions?

Thank you in advance for your help,
Jose
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