Fluids

Fluids

Topics relate to Fluent, CFX, Turbogrid and more

volume fraction method

    • Prashant Jha
      Subscriber

      Hello all, I am tring to do simulation of multiphase flow and have defined the phases. My phases are one on top of other, but when i preview my phase distribution before starting the simulation then between two phases no sharp interface is there. I have attached the image for reference. Any clue on why this is happening and how to rectify it.

    • SRP
      Ansys Employee

      Hi,

      Try to patch phase by creating appropriate region or you can create separate zone to patch regions.

      Thank you.

    • Prashant Jha
      Subscriber

      i think i have done so. I first marked the three regions in the cell registers options and then patched the phases with their respective regions. 

    • SRP
      Ansys Employee

      Hi, 

      Can you try to plot contours and share here for single phase individually just to verify how it is displayed?

      Thank you.

    • Prashant Jha
      Subscriber

      also, when i run the simulation, then after about 25 time steps, that gree color distortion appears and it becomes perfectly flat, but actually the sharp interface should be there from the beginning.

    • SRP
      Ansys Employee

      Hi,

      Can you please try to replot the contours keeping nodes values off? 

      And can you share the patching setting that you have incorporated?

      Thank you.

    • Prashant Jha
      Subscriber

      yes, now i can see the problem, when i turned off the node values.

      For patching, in the patch window, for phase 2, i am giving value 1 to region of phase 2 and value 0 to regions of phases 1 and 3. Similarly, for phase 3, i am giving value 1 to region of phase 3 and value 0 to regions of phases 1 and 2.

    • SRP
      Ansys Employee

      Hi,

      Great. Be careful during patching as only the secondary phase volume fraction is solved in case of VOF. Primary phase volume fraction is deduced from secondary phase volume fraction.

      Thank you.

    • Prashant Jha
      Subscriber

      ok so the values which i am giving for patching are correct??

       

    • SRP
      Ansys Employee

      Hi,

      Looks good. Try running to get your desired results and check ansys user's guide: 25.3. Setting Up the VOF Model (ansys.com)

      And theory manual for more details: 14.3. Volume of Fluid (VOF) Model Theory (ansys.com)

      Thank you.

Viewing 9 reply threads
  • The topic ‘volume fraction method’ is closed to new replies.