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[ICEM] Structured Hexa Mesh on Wing

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Old   August 5, 2013, 10:22
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I took a look on your case. It is not possible to get good hexa with such angle.
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Old   August 9, 2013, 11:10
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Hi Far,
I scratch my head on for a while on that geometry. Finally I was able to reach a quality > 0.25 - 0.3

On the tail on the wing section I recreate your blocking strategy (two blocks tangent to for a diamond) and than I select each faces of them and under
edit block --> convert block type --> I chose type Y block and in the image attached you can see how it looks like

If anyone has other advices how to improve the quality, I attach the .blk and .tin files if you want to see (I reckon my blocking is a bit ..messy )
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File Type: jpg Image.jpg (55.1 KB, 29 views)
Attached Files
File Type: zip wing(.tin).zip (82.9 KB, 16 views)
File Type: zip wing(.blk and .prj.zip (23.4 KB, 8 views)
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Old   December 22, 2013, 06:24
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Method 2

http://www.4shared.com/rar/qXCmda1T/file.html

In this method, O block around wing is created first (blocks collapsed in previous step at trailing edge), then tip block is split into two parts one for leading edge and one for trailing. For trailing edge block with 3 edges, Y-block is inserted. For the leading edge block, O-block is applied. See attachments and Figs.

Now working on method 3, that is not to use the collapse block command and simply creating O-block around air foil assuming trailing edge is also round.






I also tried to generate the mesh in this way. But the problem is the trailing edge angle for my airfoil is lower than 18 degrees (I model the airfoil NACA 2412). So even though you use the Y-block, you still have the smallest grids angle lower than 18 degree. Any thought about this trailing edge angle constraint? How to solve this problem without introducing GGI?
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Old   December 22, 2013, 07:01
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Quote:
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I also tried to generate the mesh in this way. But the problem is the trailing edge angle for my airfoil is lower than 18 degrees (I model the airfoil NACA 2412). So even though you use the Y-block, you still have the smallest grids angle lower than 18 degree. Any thought about this trailing edge angle constraint? How to solve this problem without introducing GGI?
Collapse the block in trailing edge. And in the trailing edge block converte mesh to free type.
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Old   February 3, 2014, 11:59
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Collapse the block in trailing edge. And in the trailing edge block converte mesh to free type.
What do you mean by free type? Unstructured grids?
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Old   February 3, 2014, 12:03
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yes. It will improve quality in the regions where hexa mesh wont fit...
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Old   February 3, 2014, 12:08
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yes. It will improve quality in the regions where hexa mesh wont fit...
I tested GGI for different AoA. GGI works well for the wing tip interface (at least for my case). So I have a feeling that actually we don't need those complex grids generation strategy at all.

Another way to solve this problem is to round the very tiny small trailing edge tip. It is widely known in the airfoil aerodynamics that rounding of trailing edge tip slightly won't change its performance and the flow. And also there is manufacturing tolerance. So it can't be perfectly sharp naturally.
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Old   February 3, 2014, 12:16
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Yes you are correct.

GGI works fine with new software technology

Sharp angles are possible to manufacture in reality...
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Old   February 4, 2014, 05:44
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Yes you are correct.

GGI works fine with new software technology

Sharp angles are possible to manufacture in reality...
Yes. Sharp angles can be manufactured. But the radius of the sharp trailing edge will still naturally exist (like 0.01 mm or even smaller). We can just use that tiny radius in CFD. Then we won't have to model the sharp angles and use Y block anymore even though our grids at the trailing edge might have to be very small to capture the radius. But we won't run into any grids quality problem any more. This also reduces the grids generation complexity.
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ICEM Hexa meshing tutorial - Wing with sharp trailing edge This thread Refback October 18, 2013 03:30

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