# Zero solution by solving the Laplace problem on part of the mes

**URL:** <https://community.freefem.org/t/zero-solution-by-solving-the-laplace-problem-on-part-of-the-mes/3018>\
**Category:** General Discussion\
**Created:** [March 7, 2024, 12:30am UTC](https://community.freefem.org/t/zero-solution-by-solving-the-laplace-problem-on-part-of-the-mes/3018 "2024-03-07T00:30:33Z")\
**Posts on this page:** 1\
**Showing post:** 11

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**Author:** ![marchywka](https://avatars.discourse-cdn.com/v4/letter/m/ee59a6/32.png) [@marchywka](https://community.freefem.org/u/marchywka)\
**Post date:** [March 7, 2024, 2:26pm UTC](https://community.freefem.org/t/zero-solution-by-solving-the-laplace-problem-on-part-of-the-mes/3018/11 "2024-03-07T14:26:57Z")

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yes, you need to fix the boundary conditions to get an exact match.  
See “natural boundary conditions” to get them for the road-only example.  
I took some of this and your mesh and ended up with this code  
[Transport-mod.edp](https://community.freefem.org/uploads/short-url/5YSdVTwYWja95nOTkAveIze98b7.edp) (3.9 KB)

[https://community.freefem.org/t/normal-boundary-condition/341](https://community.freefem.org/t/normal-boundary-condition/341)

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