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Fluids

Fluids

Topics related to Fluent, CFX, Turbogrid and more.

FLUENT: low-Re turbulence models

    • sandra.boetcher
      Subscriber

       I am working in Version 19.2 and I noticed that the low-Re turbulence models are not an option.


      There are six models available through text command:

      define/models/viscous/low-re-ke-index

      Index: 0...Abid

      1...Lam-Bremhorst

      2...Launder-Sharma

      3...Yang-Shih

      4...Abe-Kondoh-Nagano

      5...Chang-Hsieh-Chen

      Fluent uses number 3 as default.


      I am aware of this thread stating the models may be too old or unreliable and the claim that "no one has used them in the last 10 years."  Actually, in academic literature they definitely have and they reference FLUENT.  I need to use the AKN model to verify some old simulations.


      /forum/forums/topic/details-about-cin-fluent/


       

    • Rob
      Forum Moderator

      Have you turned turbulence on? Try with the ke model. 

    • sandra.boetcher
      Subscriber

      I select k-epsilon in the turbulence models.  Previously, there was a box that you could check "low Re" and the default was 3 or something in the index list above.  To change the index, you had to use the command line, which I have shown above.


      Here is what my screen looks like:



      Furthermore, looking into the command line, I see the following:



      Previously, the low-Re models were under this folder.


      Thank you for your help.  Again, this is version 19.2.


       

    • DrAmine
      Ansys Employee

      I would avoid using these old flavors of the low-Re K-Epsilon models and stick to modern Omega based approaches.


      The option appears for me in 2020R1 but only as TUI options.


       

    • sandra.boetcher
      Subscriber

      Hello Amine,


      You must have missed my initial post.  I am very much aware these low-Re k-epsilon approaches are "old." I am using it to validate against some old simulations.  Further, if they are not found under TUI in 19.2 (as shown above), why are they again found in 2020R1?

    • sandra.boetcher
      Subscriber

      This has still not been solved.

    • DrAmine
      Ansys Employee

      Even if you are doing a validation: the models are old and not recommended. They are outdated. 


      I usualy check in the current release and point release before. All other releases are not supported.

    • DrAmine
      Ansys Employee

      And the option is available in 19.2. Start from a mesh to avoid any wrong settings and activate the old low-Re K-Epsilon models


       

    • sandra.boetcher
      Subscriber

      And the option is available in 19.2. Start from a mesh to avoid any wrong settings and activate the old low-Re K-Epsilon models


       I saw your last post before you edited it.  I am looking in the turbulence-expert folder. I don't see any low-Re models there.  Please see screenshots above.


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