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question about the mesh

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in comsol i have made a 3D model:
There are two Geometries, a big sphere and a small cylinder in the sphere.
the mesh of the sphere can be made coarser, it's not important.
for the mesh of the cylinder, i want to make the edge of the bottoms of the cylinder feiner but in centre coarser.

i have tried to use the "boundary layer" to make the mesh for the cylinder. And then used the “Free Tetrahedral” to mesh the rest. but it doesn't work. only "Free Tetrahedral" is working and “boundary layer” hat no effect.

so how can i reach my goal? thank you for your help!

4 Replies Last Post 30 déc. 2013, 20:48 UTC−5

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Posted: 1 decade ago 23 déc. 2013, 09:05 UTC−5
Hello,

Two possibilities,
- your visualisation of the mesh is not good, the boundary meshes are created in the volume bur you cannot see them because you see only mesh on surface
- or, your boundaries layers are not enough small compared to the volumic mesh of the cylinder

Try some tests on geometries where you can see in the volume itself

Julien
Hello, Two possibilities, - your visualisation of the mesh is not good, the boundary meshes are created in the volume bur you cannot see them because you see only mesh on surface - or, your boundaries layers are not enough small compared to the volumic mesh of the cylinder Try some tests on geometries where you can see in the volume itself Julien

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Posted: 1 decade ago 25 déc. 2013, 19:16 UTC−5
hi, merry christmas !
thank you for your answer.
if i can only see the mesh on the surface, how can i prove that the boundary mesh has effect?
hi, merry christmas ! thank you for your answer. if i can only see the mesh on the surface, how can i prove that the boundary mesh has effect?

Jim Freels mechanical side of nuclear engineering, multiphysics analysis, COMSOL specialist

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Posted: 1 decade ago 28 déc. 2013, 22:18 UTC−5
Use free mesh first, then add the boundary layer mesh over the free mesh (it will move the free mesh over and insert the boundary layer mesh to your specifications). Try a simple example first, then expand to your problem.
Use free mesh first, then add the boundary layer mesh over the free mesh (it will move the free mesh over and insert the boundary layer mesh to your specifications). Try a simple example first, then expand to your problem.

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Posted: 1 decade ago 30 déc. 2013, 20:48 UTC−5

Use free mesh first, then add the boundary layer mesh over the free mesh (it will move the free mesh over and insert the boundary layer mesh to your specifications). Try a simple example first, then expand to your problem.


thank you for your answer, i just have one more question: which methode can i use in my case except "Boundary layer"?
thanks!
[QUOTE] Use free mesh first, then add the boundary layer mesh over the free mesh (it will move the free mesh over and insert the boundary layer mesh to your specifications). Try a simple example first, then expand to your problem. [/QUOTE] thank you for your answer, i just have one more question: which methode can i use in my case except "Boundary layer"? thanks!

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