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-   -   Mesh refinement for a cylindrical mesh (http://www.cfd-online.com/Forums/openfoam-meshing-blockmesh/84113-mesh-refinement-cylindrical-mesh.html)

lindstroem January 20, 2011 06:54

Mesh refinement for a cylindrical mesh
 
Hi Foamers,

although I have read a lot oft posts concerning this topic, I couldn't really find an answer. Therefore sorry if it maybe was already answered!

I have created the attached mesh using blockMesh:
http://dl.dropbox.com/u/587565/cylmesh_demo.png

What I now want to do is to refine a certain area at the corner of the mesh.
Earlier I had a cube where I could refine a specified area easily using the cellSet command, but in this case, the structure of my mesh gets lost. Is there a similar tool to refine certain areas which are not "box-shaped"?

Thanks!

lindstroem February 4, 2011 08:42

little workaround is with cellSet and refineMesh with a local coordinate system. But I'm still interested in other suggestions about how to get around that cellSet only allows boxToCell, which is not optimal for the mentioned geometry.

Greetings

hardykalyan February 7, 2011 17:55

Quote:

Originally Posted by lindstroem (Post 293647)
little workaround is with cellSet and refineMesh with a local coordinate system. But I'm still interested in other suggestions about how to get around that cellSet only allows boxToCell, which is not optimal for the mentioned geometry.

Greetings


cellSet also has cylinderTocell option which can extract the cells in the cylinder regions specified

lindstroem February 10, 2011 09:31

Hi thanks for the hint! Coudl you help me with the syntax? I havent found any use of it so far...

Thanks!

lindstroem February 10, 2011 14:16

Usage: cylinderToCell (p1X p1Y p1Z) (p2X p2Y p2Z) radius
Select all cells with cell centre within bounding cylinder

Teemo July 30, 2012 09:00

hi lindstroem,

I tried cylinderToCell to generate cylinder but the boundary is not smooth (https://docs.google.com/drawings/d/1...DW5AXeEmY/edit)since I used blockMesh to set the domain, do you have any idea about how to set the region instead of blockMesh?

Regards,
T

lindstroem July 30, 2012 09:06

Hi Teemo,

you want to "generate a cylinder"? some options are snappyHexMesh or O-Grids for cylinders (can be done with blockMesh). But I do not undersant your actual problem..

Greetings
L

Teemo July 30, 2012 09:19

Hi Lindstroem,

Sry for the bad description, I would like to test the wave load on the simplified floating cylinder-shape structure in a water tank, so I used one block to generate the whole tank and then employed toposet with cylinderToCell source to model the vertical floating object, while in paraview, you will see that the boundary of the cylinder is not smooth as as the mesh is made of only cuboidal cells(https://docs.google.com/drawings/d/1...DW5AXeEmY/edit).

Thanks,
T

Teemo July 30, 2012 09:34

Hi again,

Could you link me any tutorial of using snappyHexMesh or O-grids for cylinders?

Many Thanks!

lindstroem July 30, 2012 10:08

I'm still not sure if I get you right, but the tutorial for snappy can be found by searching for snappyHexMeshDict in your tutorial folder (e.g. grep -r snappy .) and in the User Guide and for O-Grid see the forum:
http://www.cfd-online.com/Forums/ope...disc-like.html

But if you select your cells after creation I don't know how you could get rid of the staggered bubble.. if it is just the phase fraction, it will be "smooth" after the first iteration.

Greetings

Teemo July 30, 2012 12:03

Hi Lindstroem,

Sry for my bad English, it is not my first language.
The video linked below is what I would like to simulate.
http://www.youtube.com/watch?v=AuNWovYR6WA

My problem is :In my case, Firstly the wave tank are meshed by BlockMesh (just one block). Then I model the cylinder by using cylinderToCell but the cylinder boundary are not smooth since all cells created by blockMesh are cube.(https://docs.google.com/drawings/d/1...e6NzNv1hk/edit)

lindstroem July 31, 2012 04:24

Yes, I would recommend snappyHexMesh (sHM) for that: So you use your inital block you created and within your sHMDict you define the cylinder you want to cut.. Then let sHM do the work for you and simulate your waves.

Greetings
L


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