# Example of submesh and DG

**URL:** <https://fenicsproject.discourse.group/t/example-of-submesh-and-dg/18214>\
**Category:** General\
**Created:** [September 16, 2025, 12:35pm UTC](https://fenicsproject.discourse.group/t/example-of-submesh-and-dg/18214 "2025-09-16T12:35:09Z")\
**Posts on this page:** 1\
**Showing post:** 2

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**Author:** ![dokken](https://yyz2.discourse-cdn.com/free1/user_avatar/fenicsproject.discourse.group/dokken/32/1560_2.png) [@dokken](https://fenicsproject.discourse.group/u/dokken)\
**Post date:** [September 16, 2025, 5:34pm UTC](https://fenicsproject.discourse.group/t/example-of-submesh-and-dg/18214/2 "2025-09-16T17:34:13Z")

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Here you are hitting an issue that relates to: [Discontinuity at interface using mixed domains - #2 by dokken](https://fenicsproject.discourse.group/t/discontinuity-at-interface-using-mixed-domains/15040/2)  
which has several workarounds required for coupling across the submeshes.

The support for this has been greatly improved in DOLFINx main branch, see for instance:

> <https://github.com/jorgensd/presentations/blob/main/icosahom/code/emi_primal_single.py#L89-L152>

where this coupling over interior submesh boundaries have been simplified greatly (copmared to my aforementioned implementation from 2024).

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