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Old   February 29, 2012, 01:51
Default SnappyHexMesh
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Hi all

I created a stl file of a square cylinder to test the snappyHexMesh function. I created my domian first using the blockMesh. That was OK. Then I placed my stl file in the trisurfacemesh folder. Then I ran snappy hexMesh

The messages indicate that there is no error, but when I open using paraFoam all I get is a square cylinder meshed without the domain.



What is wrong ?


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Old   February 29, 2012, 05:04
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Is your point from which you start meshing inside the cylinder? is your blockmesh at the right position of the stl surface? you can check that by opening your stl surface while you have your blockmesh open in parafoam.
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Old   February 29, 2012, 06:04
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Did you use sHM with the "-overwrite" option? If not, you get 2 more timestep folders 1 and 2. In there you will find your castellated and your snapped mesh. (choose the timesteps in paraview)
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Old   February 29, 2012, 17:59
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Hi

I generated my blockmesh and then I opened it using parafoam. Then I opened the stl file and then checked the position and orientation of the stl object with the domain. Everything is fine. I then use snappyhexmesh.

I looked at the different time folders also.

I find this problem only with simple geometry such as a square cylinder or cube. When I use a complicated stl file downloaded from the internet then it works fine.

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Old   February 29, 2012, 18:06
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Hi

Is this a possible bug in the software ?


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Old   February 29, 2012, 18:52
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Quote:
Originally Posted by CFD_user_2012 View Post
I find this problem only with simple geometry such as a square cylinder or cube.
If it's simple and small, then upload the case before running blockMesh and snappyHexMesh, so we can look at it and tell you if it's just a usage problem or a bug.

Best regards,
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Old   February 29, 2012, 19:54
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have you checked that the point that tells to sHM the inside of the volume domain is palced in a reasonable position and not in your stl? can you post some pictures of the error you are having?
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Old   February 29, 2012, 22:47
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Hi

OK this is my file. Let me know whats wrong



thanks
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File Type: gz test_cylinder.tar.gz (14.2 KB, 16 views)
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Old   March 2, 2012, 08:31
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Hi CFD_user,

Instead of:
Code:
    refinementBox
    {
        type searchableBox;
        min (-100.0 -0.7 0.0);
        max ( 80.0  0.7 20.5);
    }
Use something like:
Code:
    refinementBox
    {
        type searchableBox;
        min (-100.0 -0.7 0.0);
        max (282  233 256);
    }
I used ParaView's "Menu->Sources->Ruler" to see where these points are. This box now properly covers the cube, to give enough resolution for snapping things later.

Then, instead of:
Code:
    locationInMesh (0.3 30 0.43);
Use:
Code:
    locationInMesh (752.1231 300.3423 300.4234);
I used the "Menu->Sources->Sphere" for seeing where this point was. This point is nowhere near the cube and is in a position where:
Code:
    // NOTE: This point should never be on a face, always inside a cell, even
    // after refinement.
You should learn (as soon as possible!), to pay more attention to the numbers you are using! They can be your friends if you use them right; but if wrongly used, then your worst nightmares can come true

Best regards,
Bruno
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Last edited by wyldckat; March 3, 2012 at 10:47.
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Old   March 4, 2012, 23:09
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Hi Bruno

Thanks very much, works perfectly.


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Old   March 8, 2012, 08:48
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hi bruno,

thx for your post!
you helped me a few times and your discriptions are very good
I learn everytime something new if i read your posts (here using paraview to see the points)!

THX

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