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How many layers with inflation method are necessary for the boundary layer without wall functions?

    • Deus Ex Machina
      Subscriber

      Hello everyone

      I'm studying boundary layer. When I do an analysis in order of magnitude I get the classic dependence of a thin plate as inverse of the square root of the Reynolds number, therefore I know the thickness.

      So how many cells do I need to model the boundary layer with this thickness? For example, if I calculate thickness of momentum boundary layer of 1 milimeter how many cells should I have between surface and the exterior flow outside of boundary layer? I readed about 10 or 15 layers (inflation method) but I dont know if it is correct.

      Thanks for everything.

    • Rob
      Ansys Employee

      Try varying between 5 & 20 layers and report back. 

    • Deus Ex Machina
      Subscriber

      Thank you very much for the feedback.

      But once I change the number of layers, how do I know if this is the right value?

      For example, I have a thin plate. I calculate the thickness of the momemtum boundary layer about 1 millimeter so I choose 1/15 mm for the first node over the plate, so how do I know it is correct?

    • Rob
      Ansys Employee

      Does the answer change between the solutions? 

    • Deus Ex Machina
      Subscriber

      Does the answer change between the solutions?



      I understand the idea and what you mean. Thank you very much.


      Best regards.

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