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[snappyHexMesh] Create Cylinder (HOLLOW NO MESH OR CAVITY) inside a Cuboid

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Old   August 5, 2017, 10:25
Red face Create Cylinder (HOLLOW NO MESH OR CAVITY) inside a Cuboid
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sandy
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hello foamers
i have an interesting problem to discuss with you all.
1. i am having a cuboid of 10 cmx 10 cmx 10cm...which i can easily make in blockmesh.
2. i have to create a cylinder which lies entirely inside the cuboid close to the bottom. its dia is 1 cm and length 6 cm so it lies inside the cuboid.
3.i have to give boundary condition to this cylinder surface. so its a wall here

how do i delete the mesh of this cylinder, the cylinder is not supposed to have mesh inside
how do i define a patch of cylindrical surface, so i can give bc in 0 folder

the issue is: i cannot do so using blockmesh which is very tiring and prone to mistakes

i am trying to use cell set by deleting the cells using cylinder to cell
and define a patch using cylinder to cell
but i don't know exactly how to write this procedure using toposet dict
please help me foamers
i really need to get this done
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Old   August 6, 2017, 06:10
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i'm so glad i did it...
however i ran into another minute issue
when i create the cylinder
the mesh around it is irregular and nott a perfect circle.
how ca i smooth these faces to get the smooth circle...not exactly..but how can i improve this??
collapse edges or what??
image is attached here
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Old   August 6, 2017, 14:08
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i tried more refinement but still the circumference of circle contues to be irregular
my conclusion is: it can't be done using refinement or toposet or blockmesh
only way is
use .stl file of cylinder inside a cuboid
next use snapphexmesh to get the job done
will keept his thread updated
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Old   August 7, 2017, 21:19
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Hi,

If you know there is going to be cylinder in your geometry, then you can use blockMesh to create a mesh that has a cylinder. That way you can avoid the issue with irregular cells.

Cheers,
Antimony
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Old   August 8, 2017, 10:15
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Quote:
Originally Posted by Antimony View Post
Hi,

If you know there is going to be cylinder in your geometry, then you can use blockMesh to create a mesh that has a cylinder. That way you can avoid the issue with irregular cells.

Cheers,
Antimony
i know can be done using blockmesh. but there is a problem. to get a cylinder completely inside the cube. you have to create different regions and write their numbering and its a whole lot tedious. job and once you get your numbering wrong/mistype. blockmesh will kill you with flurry of errors.
i am thinking about using snappy hex mesh using .stl file
if u have any simple beginner tutorials using a cylinder, could you point me in that direction???
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Old   August 8, 2023, 07:10
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Hi, can you please explain how did you extract the mesh inside the cylinder from your general mesh?
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cellsets, cylinder domain, mesh manipulation, toposetdict

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