# Mesh Challenges: Non-drawable Sections and Outer Ring Uniformity

**URL:** <https://community.freefem.org/t/mesh-challenges-non-drawable-sections-and-outer-ring-uniformity/3620>\
**Category:** General Discussion\
**Created:** [December 8, 2024, 3:26pm UTC](https://community.freefem.org/t/mesh-challenges-non-drawable-sections-and-outer-ring-uniformity/3620 "2024-12-08T15:26:40Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![MariamiMamgo](https://yyz2.discourse-cdn.com/flex030/user_avatar/community.freefem.org/mariamimamgo/32/2641_2.png) [@MariamiMamgo](https://community.freefem.org/u/MariamiMamgo)\
**Post date:** [December 8, 2024, 3:26pm UTC](https://community.freefem.org/t/mesh-challenges-non-drawable-sections-and-outer-ring-uniformity/3620/1 "2024-12-08T15:26:40Z")

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Hello, everyone,

In the EDP file I am working with, I am encountering two issues:

1. **Incomplete Mesh** : I am unable to build the entire mesh. Specifically, the lower half remains non-drawable. Could someone explain why this is happening? When I set `r5 = 20.01`, everything seems to work correctly. Is there an alternative solution that doesn’t involve changing the radius?
2. **Non-uniform Mesh in Outer Ring** : In the outer ring, the mesh is not uniform. What could be causing this issue, and how can it be resolved?

Thank you for your assistance!  
[question\_for\_forum.edp](https://community.freefem.org/uploads/short-url/tkyvp8OTrryFZmQ5QUkyG9w4Rr3.edp) (1.2 KB)

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**Author:** ![quentin](https://avatars.discourse-cdn.com/v4/letter/q/e47c2d/32.png) [@quentin](https://community.freefem.org/u/quentin)\
**Post date:** [December 9, 2024, 4:46am UTC](https://community.freefem.org/t/mesh-challenges-non-drawable-sections-and-outer-ring-uniformity/3620/2 "2024-12-09T04:46:21Z")

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1. [question\_for\_forum.edp](https://community.freefem.org/uploads/short-url/hIBWKCquNKrt36fjRg02gQZONvP.edp) (1.3 KB)  
In the modified file, `circle5` is replaced by `circle5a` and `circle5b`, each of them corresponds to a semicircle.
2. `buildmesh` may not create a uniform mesh automatically. In FreeFEM, one workable way I know is to use `square` together with `movemesh`. In addition, you can use Gmsh.