Fluids

Fluids

Mesh generation errors when Growth Rate > 1.1 with structured 2D mesh

    • oll5hbdfk
      Subscriber

      Hello everyone,

      I want to simulate a 2D airfoil using a structured C-mesh similar to this one. Therefore I made a couple of sizings with a fixed number of divisions and a Multizone Quad/Tri Method. Overall the mesh looks correct, but in the area close to the airfoil the growth rate of the cells is strange as shown in this image:

      Also I get this warning:
      The following entities with objects scoped to them were unable to have mesh data correctly associated with them. Try removing the object scoped to these entities or try another mesh method to get a successful mesh.
      Project > Model > Geometry > Surface Body > Surface Body

      I found out that it has to do with the growth rate of the sizing orthogonal to the surface (actually boundary, since it's 2D) of the airfoil. If I set it to 1.1 it looks fine:

      Though I still get the warning from above (so maybe it's unrelated). The threshold seems to be around 1.11.

      What am I doing wrong?

    • Keyur Kanade
      Ansys Employee

      If you are using Multizone for 2D and want quad then please select 'All Quad' under Free Face Mesh Type. 

      Plus it is not clear if you are using inflation or edge biasing. 

      You can use inflation control to get boundary layer. 

      If it is all mapped mesh then edge biasing will also help. 

      Please go through help manual for more details 

      Please check following videos

      Ansys Meshing Sizing:

      Ansys Meshing: Meshing Methods:

      Ansys Meshing: Inflation:

       

      Regards,

      Keyur

      How to access Ansys Online Help Document

      Guidelines on the Student Community

       

       

    • oll5hbdfk
      Subscriber

      I already have it set to "all quad". Let me give you some more information. These are the sizings with bias:

       

      red:

      blue:

      BTW: The same ussie occures when I chose a high "Bias Factor" isntead of "Smooth Transition"

      All edges have sizings. The ones without Bias have a fixed number of divisions similar to this:

      The Multizone Method looks like this:

    • Keyur Kanade
      Ansys Employee

      Are you using 2022R2?

      Please try soft sizing at edges. Please check your global sizing as well. 

      Have you tried inflation? Please check that as well. 

      Please go through help manual for more details 

      Regards,

      Keyur

      How to access Ansys Online Help Document

      Guidelines on the Student Community

       

    • oll5hbdfk
      Subscriber

       

      Thanks for your help.

      I set the red sizing to soft and it helps with the boundary layer:

      The problem is that it destroys the mesh in front of the airfoil:

      Also now the cells also shrink towards the top edge of the domain which I don’t want. That’s also why I left the other sizings “hard” or else they’d also grow from both sides.

      Another way to stop them growing like that seems to be to set the global sizing to “Use Adaptive Sizing”, but then i have the issue with the inflation layer again and the mesh is also broken:

      I’m using 2021R1, but I can upgrade if you think that helps

       

    • oll5hbdfk
      Subscriber

      I think I got it. Using "Face Meshing" instead of a MultiZone Method seems to work much better

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