Fluids

Fluids

volume fraction of a scalar in Hexahedron mesh and in Tetrahedron mesh

    • Kadhim
      Subscriber

      Hi everyone,


      I would really appreciate if anyone can help me with my issue.


      I am using ansys cfx to create a planar jet flow, injecting methane a atmospheric air and then indicate the volume fraction of methane in the domain. when I create a structured mesh (Hexahedron one), I got the a constant value of volume fraction which is (one) (which is wrong results), however, when I change the mesh to be a Tetrahedron shape (with same B.C), i got good result but not symmetric as it should be. moreover, the velocity profile for both cases is the same and it is correct.


      if anyone face kind of problem, please share your opinion with me. I attached the tow results as well in the pictures.  


       


    • Rob
      Ansys Employee

      Please add the images into your post: staff are not permitted to open attachments. 

    • Kadhim
      Subscriber

      I did, can you see them now?

    • DrAmine
      Ansys Employee
      More details about domain settings model and bc please.
    • Kadhim
      Subscriber

      i am using k-e model for now, the domain is like a cylinder with L=1.5 m and outer diameter D=0.4 m, initial conditions are V (volume fraction) = 0 for methane and = 1 for air. more details are in bellowing picture  

    • DrAmine
      Ansys Employee
      Why using multiphase approach for gases? You should model this by multicomponent gaseous mixture.
    • Kadhim
      Subscriber

      but I am using CFX and there is no such option

    • DrAmine
      Ansys Employee

      There is an option if you define a mixture material. Have a look in the standard tutorials.

    • Kadhim
      Subscriber

      and it is isothermal process, energy equation is off

    • Kadhim
      Subscriber

      Can you please send me any link coz I don't have an access to the tutorials 

    • DrAmine
      Ansys Employee

      Tutorials are on the Help Website. Wherever you are in CFX just hit "F1" and you get directed to the help (assume you are working with a newer ANSYS Release). I cannot share any tutorials on this community.

    • DrAmine
      Ansys Employee
    • Kadhim
      Subscriber

       trying to get the tutorials, but do you think  it is the reason of my problem?

    • DrAmine
      Ansys Employee
      Might be.
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