[ICEM] Trailing edge meshing problems

juanchope · June 11, 2014, 12:54

Hi!

I'm trying to mesh airfoil with octree algorithm but i'm having troubles to mesh it near the trailing edge, elements does not stick to the edge. Geometry es composed by an upper surface (green), a lower surface (red) and there is a small surface on the trailing edge (blue or purple).

The images show my problem (had problems to attach them as a file)

https://www.dropbox.com/s/o1rrdhpohmt3qq4/img1.jpg
https://www.dropbox.com/s/ng010rl655qqyta/img2.jpg
https://www.dropbox.com/s/lutvumc64t0j5aj/img3.jpg

The last one is as it looks when I import it to fluent, it is easily noticed that there is one (or few) elements missing:

https://www.dropbox.com/s/8m9m63g3mxjvn0w/img4.jpg

As i have read in another post, i tried reducing the edge criterion on the octree algorithm but I can do it only to 0.11, if try to set it lower, degenerated elements start to appear on the meshing process.

Also I tried to reduce my mesh size (by reducing the scale factor) but I come to the same result, degenerated elements during the meshing process.

The same thing for cells in the gap, as soon i set more than 3 cells in the gap, it creates degenerated elements.

Every time it founds degenerated edges the mesh is useless as even the volume inside the airfoil tries to be meshed.

Hope anyone can help me!

Thank you!

yonchong · June 19, 2014, 09:04

Did you try the "thin cut" option.

Global Mesh Setup -> Volume Mesh Parameters -> Define thin cuts.

If you are going to use it read the manual first because you have to have seperate part for two surfaces and the line bordering the surfaces.

Other option is read back the mesh but only surface mesh only.

File -> Mesh -> Open Surface Shell Only

Then manually fix the surface mesh using options in Edit Mesh.

The rebuild the volume mesh using Quick (Delaunay). This is much easier option than try to fix surface and volume cells together.

kad · June 19, 2014, 21:10

Define thin cuts is a good guess. I would define a node distribution for the trailing edge curve in "curve mesh setup". Choose a pretty low value for maxsize. You can preview the distribution by activating it via right mouse button on curves in the display tree. Further I would decrease sizes on the wing in general as the mesh looks very coarse.

June 11, 2014, 12:54	Trailing edge meshing problems	#1
juanchope New Member Juancho Perez Join Date: Jan 2013 Posts: 3 Rep Power: 13	Hi! I'm trying to mesh airfoil with octree algorithm but i'm having troubles to mesh it near the trailing edge, elements does not stick to the edge. Geometry es composed by an upper surface (green), a lower surface (red) and there is a small surface on the trailing edge (blue or purple). The images show my problem (had problems to attach them as a file) https://www.dropbox.com/s/o1rrdhpohmt3qq4/img1.jpg https://www.dropbox.com/s/ng010rl655qqyta/img2.jpg https://www.dropbox.com/s/lutvumc64t0j5aj/img3.jpg The last one is as it looks when I import it to fluent, it is easily noticed that there is one (or few) elements missing: https://www.dropbox.com/s/8m9m63g3mxjvn0w/img4.jpg As i have read in another post, i tried reducing the edge criterion on the octree algorithm but I can do it only to 0.11, if try to set it lower, degenerated elements start to appear on the meshing process. Also I tried to reduce my mesh size (by reducing the scale factor) but I come to the same result, degenerated elements during the meshing process. The same thing for cells in the gap, as soon i set more than 3 cells in the gap, it creates degenerated elements. Every time it founds degenerated edges the mesh is useless as even the volume inside the airfoil tries to be meshed. Hope anyone can help me! Thank you!

Similar Threads
Thread	Thread Starter	Forum	Replies	Last Post
Y-Plus values at aerofoil leading edge and trailing edge at high incidence	Engr07	Main CFD Forum	4	June 29, 2012 10:42
[ICEM] Flow channel meshing problems	StefanG	ANSYS Meshing & Geometry	19	May 15, 2012 06:44
Trouble with sharp trailing edge	Prakash.Paudel	ANSYS Meshing & Geometry	4	August 12, 2011 14:01
is free meshing or mapped meshing is best for flow problems	shanu	Main CFD Forum	0	February 18, 2010 11:58
GAMBIT: Assumption of an edge type while meshing	Agnes	FLUENT	0	June 22, 2005 13:37

June 19, 2014, 09:04		#2
yonchong Member Yon Han Chong Join Date: Jun 2012 Posts: 77 Rep Power: 13	Did you try the "thin cut" option. Global Mesh Setup -> Volume Mesh Parameters -> Define thin cuts. If you are going to use it read the manual first because you have to have seperate part for two surfaces and the line bordering the surfaces. Other option is read back the mesh but only surface mesh only. File -> Mesh -> Open Surface Shell Only Then manually fix the surface mesh using options in Edit Mesh. The rebuild the volume mesh using Quick (Delaunay). This is much easier option than try to fix surface and volume cells together.

June 19, 2014, 21:10		#3
kad Senior Member Join Date: Feb 2013 Location: Germany Posts: 200 Rep Power: 24	Define thin cuts is a good guess. I would define a node distribution for the trailing edge curve in "curve mesh setup". Choose a pretty low value for maxsize. You can preview the distribution by activating it via right mouse button on curves in the display tree. Further I would decrease sizes on the wing in general as the mesh looks very coarse.