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[ICEM] hybrid mesh of tangential inlet

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Old   October 21, 2011, 03:40
Default hybrid mesh of tangential inlet
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I want to make hybrid mesh for cyclone separators. i have attached picture of my cyclone. i have generated the multiblock structured mesh as shown in picture. if i mesh the inlet with sructured mesh then elements in the entry region are very skewed and quality is low. so i want unstructured mesh at inlet. please help me..
i dint know how to connect the nodes of structured mesh to the unstructured mesh at inlet.
please help me.
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File Type: jpg Cyclone_tangential inlet.jpg (82.0 KB, 132 views)
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Old   October 21, 2011, 05:20
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Hi
In ICEM CFD you can merge mesh in few different ways. You can generate grids separately, then load and merge both. In this way you will have non-conformal mesh. To connect nodes on contact surface go to Edit Mesh->Merge Nodes->Merge volume meshes. After this you can smooth theta elements using option Smoot mesh globally.
Other method is to leave hex mesh on contact surface and then you can generate unstructured mesh with enable Use Existing Mesh Parts and selected part contain contact surface with in. After this operation reread both meshes and connect nodes using merge nodes by tolerance. Set tolerance to some small value because these nodes have the same coordinates.
You can also watch this tutorial:
http://www.youtube.com/watch?v=KabKF...eature=related
Regards
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Old   October 21, 2011, 06:08
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thank you twix for your help... i had already gone though that tutorial but if i mesh like that then my element quality at tangential inlet is very poor. that's why i prefer hybrid mesh. is there any other way to mesh tangential inlet part.

also could you please give me the example to merge the mesh.
i will very thankful to you. please help.

also in volume merge option i come across two options. 1. merge surface mesh part & 2. frozen volume mesh part. what to do with these options. which part i have to select in that tabs. please help.

Last edited by arjun3020; October 21, 2011 at 06:56.
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Old   October 21, 2011, 07:01
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You can also use quarter O-grid block but probably in selected areas you will get bad element quality.
Regards
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File Type: jpg blocking1.jpg (56.0 KB, 77 views)

Last edited by Twix; October 21, 2011 at 07:16.
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Old   October 21, 2011, 07:06
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thank you. as you said i am getting bad quality in selected areas. that's why i am going for hybrid mesh.
i found following difficulties.

in volume merge option i come across two options. 1. merge surface mesh part & 2. frozen volume mesh part. what to do with these options. which part i have to select in that tabs. please help.
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Old   October 21, 2011, 07:31
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1. In this tab you should select the surface mesh parts to be merged (interface between two meshes).
2. You can leave it empty because hex mesh is frozen by default.
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Old   October 23, 2011, 12:50
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hi... i tried as per your suggestions but i am not able to get hybrid mesh.
i am attaching simple cube geometry. i mesh half part with blocking (hexa), and remaining part with unstructured tetra.
then i load mesh from blocking it shows dialog box showing 'mesh is already present' then i click on merge tab. then it shows mesh like image 1, then i go for merging option from edit mesh but mesh is not good (image 2) i thing i am doing some mistakes.
could you please tell me the step by step procedure in detail. please help. i will be very thankful to you.
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File Type: jpg 1.jpg (105.6 KB, 62 views)
File Type: jpg 2.jpg (91.7 KB, 77 views)
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Old   October 24, 2011, 03:15
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Hi,

First step is to build topology for your geometry. Then, create new part e.g. INTERFACE and put there contact surface, between 2 domains, only. Generate your meshes, load and merge them, then go to Merge Nodes->Merge volume mesh and in tab “Merge surface mesh parts” select your new part containing contact surface, click Apply and everything should be ok.

Regards and have fun
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Old   October 24, 2011, 10:42
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hi. i tried to get hybrid mesh. i build topology its fine. geometry is ok.then i mesh half part with hexas. while meshing remaining half part it shows that your geometry has a hole. them i press repair. but its not working. please help.
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Old   October 25, 2011, 02:01
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Hi
Probably you didn’t include part with contact surface to parts selected to meshing. This surface have to be mesh in both (hex and theta) grids. Also you have to create material point to generate theta volume mesh.
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Old   October 25, 2011, 08:51
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hi.. finally i got it. thank you so much for your help.

but while meshing my cyclone problem i find difficulties,

i am attaching the hybrid mesh of cyclone.
it is not good at inlet entry.
what should i do to have good quality mesh for cyclone.
Attached Images
File Type: jpg 2.jpg (85.7 KB, 83 views)
File Type: jpg 3.jpg (75.6 KB, 65 views)
File Type: jpg 4.jpg (97.6 KB, 69 views)
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Old   October 26, 2011, 00:30
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Hi Michal,

you have also advice me to use the quarter o-Grid, i have done few steps. but i cant proceed. i have attached picture for your reference.
now while creating y block (quarter o- grid) it ask to select 6 vertices. which vertices should i select.
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Old   October 26, 2011, 00:37
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Sorry here is the attachment.
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File Type: jpg 1.jpg (50.6 KB, 66 views)
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Old   October 26, 2011, 01:46
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Hi
Check in help, there is a picture showing vertices you should select and the order of selection.
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Old   October 26, 2011, 03:31
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i had already check the help but its not working. i followed the instruction but its not working. i managed to get y block as shown in picture, but i have problem in association of that y block.
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File Type: jpg 2.jpg (49.8 KB, 36 views)
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Old   October 26, 2011, 03:39
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also could you please help me in former issue. see reply number 12.
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Old   October 26, 2011, 04:11
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Submit your project, i will see what is wrong.
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Old   October 26, 2011, 05:53
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Hi, i am sending you my project, please see to it. thanks.
i am sending you my trial project. i am actually working on cyclone. i will mesh the cyclone as per trial project.
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File Type: zip mail.zip (28.6 KB, 12 views)
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Old   October 26, 2011, 07:27
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Hi,
I took a look at your project and you didn’t merge vertices marked in the picture. To do so you have to go to Blocking -> Merge Vertices-> Merge Vertices by Number or Tolerance, but as I wrote earlier you will have some bad elements.
Regards
Attached Images
File Type: jpg jpg2.jpg (68.7 KB, 56 views)
File Type: jpg jpg1.jpg (67.6 KB, 41 views)
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File Type: zip Tangent.zip (26.5 KB, 5 views)
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Old   October 26, 2011, 08:30
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Look at the project attached. It increases a little bit the quality.
At least, yout min angle is 18°, which is not that bad
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File Type: zip tangent_test.zip (28.9 KB, 36 views)
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