[ICEM] Unstructured 3d blade grid

papis · October 31, 2011, 12:42

Hi all,
I am trying to make an unstructured tetrahedron mesh of a rotating blade.
The problem I need to simulate is the Caradonna rotor which is a 2 bladed helicopter rotor.

As you can see from the pictured below i have generated an mesh with periodic boundaries.My main problem is the generation of grid ON the blade
As you can see the surface mesh doesn't actually fits the surface of the blade(Not all nodes of boundary faces are on the airfoil surface) which of course is problematic.

At first I thought it might be resolution but when doing hexagonal grids(with blocking for example) the surface is fitted very nicely even at low resolutions.

If anyone could point me to the right direction to understand this issue I would be grateful.
[IMG]file:///home/papis/Desktop/screen1.jpg[/IMG]

[IMG]file:///home/papis/Desktop/screen2.jpg[/IMG]

P.S. I have created only one body (the region between the blade and the outer boundary,since i do not need grid inside the blade)

Thanks a lot

papis · November 1, 2011, 06:18

Is it possible that surface meshes should be generated first?

Ludvik · November 1, 2011, 11:54

Try decrease "Edge criterion" parameters from 0.2 to 0.005 (Global Mesh Parameters > Volume Meshing (Octree) ) and/or try to use "Thin Cuts".

papis · November 1, 2011, 13:08

Yeap this improved things.Thanks a lot for you help.I read the help about the edge criterion option and it wrote " value 0.2 is adequate for most cases.".This is very misleading since 0.2 can't prescribe the surface of naca0012 blade.

Anyway's Thank a lot for your reply Ludvik

October 31, 2011, 12:42	Unstructured 3d blade grid	#1
papis New Member Papis Join Date: Dec 2010 Posts: 25 Rep Power: 15	Hi all, I am trying to make an unstructured tetrahedron mesh of a rotating blade. The problem I need to simulate is the Caradonna rotor which is a 2 bladed helicopter rotor. As you can see from the pictured below i have generated an mesh with periodic boundaries.My main problem is the generation of grid ON the blade As you can see the surface mesh doesn't actually fits the surface of the blade(Not all nodes of boundary faces are on the airfoil surface) which of course is problematic. At first I thought it might be resolution but when doing hexagonal grids(with blocking for example) the surface is fitted very nicely even at low resolutions. If anyone could point me to the right direction to understand this issue I would be grateful. [IMG]file:///home/papis/Desktop/screen1.jpg[/IMG] [IMG]file:///home/papis/Desktop/screen2.jpg[/IMG] P.S. I have created only one body (the region between the blade and the outer boundary,since i do not need grid inside the blade) Thanks a lot

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November 1, 2011, 06:18		#2
papis New Member Papis Join Date: Dec 2010 Posts: 25 Rep Power: 15	Is it possible that surface meshes should be generated first?

November 1, 2011, 11:54		#3
Ludvik Member Join Date: Apr 2009 Location: Czech Republic Posts: 65 Rep Power: 18	Try decrease "Edge criterion" parameters from 0.2 to 0.005 (Global Mesh Parameters > Volume Meshing (Octree) ) and/or try to use "Thin Cuts".

November 1, 2011, 13:08		#4
papis New Member Papis Join Date: Dec 2010 Posts: 25 Rep Power: 15	Yeap this improved things.Thanks a lot for you help.I read the help about the edge criterion option and it wrote " value 0.2 is adequate for most cases.".This is very misleading since 0.2 can't prescribe the surface of naca0012 blade. Anyway's Thank a lot for your reply Ludvik