# Meshing methodology

**URL:** <https://prepomax.discourse.group/t/meshing-methodology/2863>\
**Category:** General Questions\
**Created:** [July 21, 2025, 3:15pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863 "2025-07-21T15:15:41Z")\
**Posts on this page:** 5\
**Page:** 1

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**Author:** ![Paul18fr](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@Paul18fr](https://prepomax.discourse.group/u/Paul18fr)\
**Post date:** [July 21, 2025, 3:15pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863/1 "2025-07-21T15:15:41Z")

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Hi,

I’m performing new tests in order to have s structured mesh: how do i’ve to proceed so that the mesh resmains coïncident in the current example?

Using Sweep, i cannot impose the number of layers as in Extrude, am i correct? such option will be usefull won’t be?

Additional question: how to have only quads on the triangle surface (as in “shell gmsh”)? options seem identical but i fail all the time.

Thanks for you feedback

Paul  
[test.pmx](https://prepomax.discourse.group/uploads/short-url/t1kQ9KzjahiqMeG5Yi5PZdLvT67.pmx) (438.7 KB)

 ![mesh_pmx](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/d/d284db5defee4e16392ad88025534b332951b830.png)  
 ![mesh2_pmx](https://global.discourse-cdn.com/free1/uploads/prepomax/original/2X/8/84f3284475d0060afe897d19e91cae369d8c8ca2.png)

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**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [July 21, 2025, 4:04pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863/2 "2025-07-21T16:04:37Z")

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> [@Paul18fr](#):
>
> how do i’ve to proceed so that the mesh resmains coïncident in the current example?

It is when meshing a compound with the Transfinite algorithm. Otherwise, when there are multiple parts meshed with Extrude, Revolve or Sweep algorithms, you can use the Merge nodes tool after meshing.

> [@Paul18fr](#):
>
> Using Sweep, i cannot impose the number of layers as in Extrude, am i correct?

Yes, that’s right.

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<div class="post-metadata">

**Author:** ![Paul18fr](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@Paul18fr](https://prepomax.discourse.group/u/Paul18fr)\
**Post date:** [July 21, 2025, 4:20pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863/3 "2025-07-21T16:20:04Z")

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Thanks Jakub for your quick answer,

> [@FEAnalyst](#):
>
> when there are multiple parts meshed with Extrude, Revolve or Sweep algorithms, you can use the Merge nodes tool after meshing

that’s exactly what i would like to do, but since we cannot impose a discretization, submeshes are not coincident (i think i’ve used the same size)

> [@FEAnalyst](#):
>
> Yes, that’s right.

is it a gmsh or a pmx limitation? is it on the roadmap to propose such (usefull) features?

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<div class="post-metadata">

**Author:** ![FEAnalyst](https://yyz2.discourse-cdn.com/free1/user_avatar/prepomax.discourse.group/feanalyst/32/688_2.png) [@FEAnalyst](https://prepomax.discourse.group/u/FEAnalyst)\
**Post date:** [July 21, 2025, 4:45pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863/4 "2025-07-21T16:45:42Z")

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> [@Paul18fr](#):
>
> Additional question: how to have only quads on the triangle surface (as in “shell gmsh”)? options seem identical but i fail all the time.

In this case, you may have to disable Transfinite 3-sided faces and Transfinite 4-sided faces settings to achieve that but then the mesh won’t be structured.

Or use Sweep instead of Extrude and select Quasi-structured quad.

> [@Paul18fr](#):
>
> that’s exactly what i would like to do, but since we cannot impose a discretization, submeshes are not coincident (i think i’ve used the same size)

They don’t have to be perfectly coincident (the Merge nodes tool has a tolerance setting) but indeed they should be at least approximately coincident and you need to enforce matching numbers of elements on the common edges (using meshing parameters and local refinement).

> [@Paul18fr](#):
>
> is it a gmsh or a pmx limitation? is it on the roadmap to propose such (usefull) features?

Gmsh doesn’t have the sweep algorithm, it was developed independently in PrePoMax (although it’s based on Gmsh’s quad meshing) and it happened quite recently so it may still be improved in the near future. Feel free to create a feature request in the “green” section of the forum.

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**Author:** ![Paul18fr](https://avatars.discourse-cdn.com/v4/letter/p/35a633/32.png) [@Paul18fr](https://prepomax.discourse.group/u/Paul18fr)\
**Post date:** [July 21, 2025, 5:56pm UTC](https://prepomax.discourse.group/t/meshing-methodology/2863/5 "2025-07-21T17:56:23Z")

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> [@FEAnalyst](#):
>
> the Merge nodes tool has a tolerance setting

I know but nodes must be as close as possible; indeed one of the 2 nodes is simply moved are it may cause element quality loss