4 Replies Latest reply on Aug 4, 2010 11:57 AM by Jianhu Nie

    Turbulence Models

    1-PKJ6XI Jul 28, 2010 2:20 PM

      Hello:

       

      I have solid work flow simulation. I can see only I-L and K-epsilon as turbulence models which are very limited to many afvanced fluid mechanics problems.

       

      I am studying the flow pattern at the exit of a forwarded centrifugal fan and comparing with the experimental results

       

      This flow requires other turbulence models which don't exist in the flow simulation such as K- Omega, Reynolds stress model, Detached Eddy simulation,  LES, SST model near the wall.

       

      Please advise

       

      Samer Hassan

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        • Re: Turbulence Models
          Loic Ancian
          Loic Ancian Aug 3, 2010 6:11 AM (in response to 1-PKJ6XI)

          Hello,

          Then the answer is in your question : Flow simulation only provides K-Epsilon model (a little bit modified). So there is no other model available.

          Sorry for that.

           

          You can see in following pic the values that are used for the k-espilon. It seems that one of the parameter was changed.

           

           

          here is what I was told by support :

          "for fm we use other constant: instead of 20.5 in classical model we use 7.5. This constant was changed after numerous different calculations of flows in pipes, plates and so on in order to match test data and calculation results with our code better."

           

          Loic

            • Re: Turbulence Models
              Jianhu Nie
              Jianhu Nie Aug 4, 2010 11:44 AM (in response to Loic Ancian)

              Although SW Flow Simulation's manual mentioned it used k-e model, the one is not the standard k-e model which is requires wall-function method near the solid wall. Lam-Bremhorst model is a low-Re k-e model. With the damping function, it can be applied all the way to the solid wall. This should be good if mesh is fine enough.

                • Re: Turbulence Models
                  Ramya Ramaswamy
                  Ramya Ramaswamy Aug 4, 2010 11:49 AM (in response to Jianhu Nie)

                  Jiahnu,

                   

                  Can you please tell me how I can change the turbulence model with the damping function? Is there any good reference material that you can suggest which will help me learn more about how I can change my models?


                  Thank you

                  Ramya

                    • Re: Turbulence Models
                      Jianhu Nie
                      Jianhu Nie Aug 4, 2010 11:57 AM (in response to Ramya Ramaswamy)

                      If you want to change in SW Flow Simulation, I don't know.

                       

                      For k-e -like turbulence models, there are a number of papers. For example, AKN models in Int. J. Heat Mass Transfer, 1993 (Flow) and 1994 (Thermal). The table in previous post  by Loic is a good summary of popular ones. Actually, standard k-e model is one special case of low-Re k-e models, while the damping function is unity (one).