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Large cells at trailing edge (airfoil)

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Old   April 4, 2020, 15:24
Default Large cells at trailing edge (airfoil)
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Alessandro Donadeo
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Hi, I would like to solve the problem (I have attached a figure) of the too large cells at the trailing edge, those just following the prism layer.
Around the blade I have already inserted a volumetric control that decreases the size of the cells, also I have a curve control of the trailing edge.
How can I do? thanks
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Old   April 10, 2020, 13:13
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The best way is to split the trailing edge face as a different surface and apply a new control there.

Alternatively you can use edge proximity refinement.
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Old   April 11, 2020, 04:44
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Quote:
Originally Posted by me3840 View Post
The best way is to split the trailing edge face as a different surface and apply a new control there.

Alternatively you can use edge proximity refinement.
In which way can I use edge proximity? Are there any particular value of the parameters to be entered?
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Old   April 11, 2020, 05:11
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please read the help on mesh refinement and you will also learn other ways to improve your mesh
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Old   April 11, 2020, 05:54
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Thanks. I'm doing a volume mesh. There is no edge proximity but only surface proximity in default controls. How can I activate it?
Simcenter help says: "Edge Proximity is only available as a custom control for an automated mesh operation and is deactivated by default."

(I'm new in Star ccm+)
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Old   April 11, 2020, 06:25
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the volume mesh is created from the surface mesh so if you create a finer surface mesh then the volume mesh will be finer near that surface too - remember a good volume mesh relies on starting with a good surface mesh.
so you need to activate edge proximity in the surface remesher and its required settings.
for an airfoil you dont need many cells on that trailing edge and many foil meshes have a sharp edge.
what is far more important is the cells downstream in the wake of the whole foil and you will need to use volume sources and the wake refinement tools will help too see help topic Pre-Processing > Meshing > Custom Mesh Controls > Mesh Refinement in a Wake
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Old   April 11, 2020, 07:21
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Quote:
Originally Posted by ping View Post
the volume mesh is created from the surface mesh so if you create a finer surface mesh then the volume mesh will be finer near that surface too - remember a good volume mesh relies on starting with a good surface mesh.
so you need to activate edge proximity in the surface remesher and its required settings.
for an airfoil you dont need many cells on that trailing edge and many foil meshes have a sharp edge.
what is far more important is the cells downstream in the wake of the whole foil and you will need to use volume sources and the wake refinement tools will help too see help topic Pre-Processing > Meshing > Custom Mesh Controls > Mesh Refinement in a Wake
I understood, thanks.
I did not insert a wake control because the mesh is rotating and I noticed that the wake, instead, has a preferential direction.

I also added a complete blade offset as the control volume. I did it because I couldn't insert a control volume just for the trailing edge, as the blade is curved and I couldn't find any way to replicate a similar distorted volume.
I, therefore, thought it useful to use curve control (the trailing edge) to thicken the area. Let me know if I'm wrong with something.


I'm looking in the Surface Remesher options (photo attached) but by activating "perform proximity refinement" I can't see the "edge proximity refinement" in the default controls.
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Old   April 11, 2020, 08:29
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in the help topic Pre-Processing > Meshing > Surface Meshers > Surface Mesher Controls and Values you will read about this method and it says you need to apply it as a custom control on selected surfaces.

regarding wake refinement whatever method you use will need to be within the moving mesh rotating region so this will need to extend some distance downstream of the blade so there is no reason not to use wake refinement in the required direction in but only within the rotating region.

however i would be running a steady state version first using the moving reference frame method to add the fan momentum at the required rpm
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airfoil, mesh, t.e., trailing edge resolution

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