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[ICEM] Mesh is leaking (hole) at trailing edge of wind turbine blade

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Old   September 12, 2018, 15:06
Default Mesh is leaking (hole) at trailing edge of wind turbine blade
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ShahzadHassan
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Hi Dear All,

I really appreciate the effort and time that people spend here helping each other, which makes cfd-online as the last resort whenever i get stuck up

My problem is to analyze the flow over an Aircraft. I'd like to mention all the steps in detail here:

1. First i make its model in Solidworks
2. I then tried all method step, iges, importing to ansys design modeler to import the geometry to ICEM.
3. After importing (no curves, points etc. but only surfaces), i then visually check all surfaces to make sure that everything appears as they did in solidworks. So far so good.
4. I run build topology to extract curves and points from these surfaces with a tolerance value of '0.009' and as the smallest distance between 2 points on trailing edge is 0.9 . I get all RED lines everywhere except for a few YELLOW ones which i repair manually. At the end, i still have 3 to 4 YELLOW lines which cant be repaired. I zoom in and find that some of these YELLOW lines are single whereas some are double(when magnified). i leave the single ones as it is and delete one from all double YELLOW curves which could not be repaired.
5. I now assign different max mesh size to all surfaces individually, depending upon their shapes and sizes, so that the geometry is adequately represented.
6. I set the global surface mesh method to All TRi Patch Independent.
7. I set global volume mesh method to ROBUST OCTREE. To avoid sharp trailing edge of the blade i cut a flat surface on the trailing edge and give very small mesh size on it.
8. I define material point 'ORFN' inside the hub and inside of the wind turbine blades. I also define material point 'FLUID' by selecting centroid of two domain points within the area where overall blades will rotate.
11. I hit compute volume mesh and wait for the mesh to generate. During meshing, i see a lot of errors appearing in the message window at the bottom but the mesher keeps on running.
12. After computing volume mesh which sometime takes more than an hour, i get this message; YOUR GEOMETRY HAS A HOLE, DO YOU WANT TO REPAIR IT? When i try to repair, i see a lot of holes (in thousands) which even i tried to repair individual elements by using mesh editing tools available such as merge nodes etc but that is impractical as the holes are far too many to repair. (While repairing, i delete all volume elements so that im only left with the surface mesh)

Sorry for such a long post, but i wanted to mention all the tiny bits and details intentionally for troubleshooting purpose.

Now i have these questions:

1. What am i Doing wrong with this supposedly simple problem? I have tried change tolerances, importing model from solidworks in various different formats but this problem still persists.

I am attaching my icem model file link if anyone can open this up and help me also i attaching the region where holes are appearing ( mesh is leaking outside of blades)

link to onedrive folder of my icem file ( it contains this model) is attached: https://1drv.ms/f/s!AnN5QFdsfuRZmQvABsTq1IPVdJU6
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File Type: jpg Screenshot (311).jpg (83.2 KB, 46 views)
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Old   September 13, 2018, 05:26
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Gert-Jan
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I loaded it in v19.1. Opened Settings>Model/Units and set the Topo Tolerance to 0.005 and the Triangulation to 1e-5.
Then my computer has no problems with your case at all, see picture.
You only need some refinement on the leading edges. Also, it might be helpful defining "Thin Cuts", see Mesh>Global Mesh Parameters>Volume Meshing Parameters.
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Old   September 13, 2018, 05:40
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can you send me your file after you did mesh on my geometry on a dropbox or onedrive ? What do mean by leading edge as i don't have a leading edge curve in my geom
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Old   September 13, 2018, 05:47
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Quote:
Originally Posted by Gert-Jan View Post
I loaded it in v19.1. Opened Settings>Model/Units and set the Topo Tolerance to 0.005 and the Triangulation to 1e-5.
Then my computer has no problems with your case at all, see picture.
You only need some refinement on the leading edges. Also, it might be helpful defining "Thin Cuts", see Mesh>Global Mesh Parameters>Volume Meshing Parameters.

please can you send me the meshed file usign dropbox or onedrive at "12pwmec3326@gmail.com" need to see what size you gave to trailing edge and whether you defined thin cuts
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Old   September 13, 2018, 05:50
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I mean the leading edge of your propellor wing, see my pictures uploaded previously. The curvature is not captured very well by the elements.


You can download it here: https://we.tl/t-SSrc9cpZhw
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Old   September 13, 2018, 05:52
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I did nothing on sizing or thin cuts. just used your geometry. Only set topotolerance and triangulation
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icem 18.1, meshing 3d, turbine blade, unstructured mesh

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