# Incompressible Navier-Stokes with GMSH: Found no facets matching domain for BC

**URL:** <https://fenicsproject.discourse.group/t/incompressible-navier-stokes-with-gmsh-found-no-facets-matching-domain-for-bc/1371>\
**Category:** mesh\
**Created:** [August 20, 2019, 8:10pm UTC](https://fenicsproject.discourse.group/t/incompressible-navier-stokes-with-gmsh-found-no-facets-matching-domain-for-bc/1371 "2019-08-20T20:10:33Z")\
**Posts on this page:** 1\
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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:** [August 21, 2019, 8:39pm UTC](https://fenicsproject.discourse.group/t/incompressible-navier-stokes-with-gmsh-found-no-facets-matching-domain-for-bc/1371/2 "2019-08-21T20:39:12Z")

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I am not at a computer right now, so cant tell you why your snippet doesn’t work. However, as you use Gmsh, you are able to mark the Facets for each boundary there. These can be loaded to dolfin with meshio. See [Transitioning from mesh.xml to mesh.xdmf, from dolfin-convert to meshio](https://fenicsproject.discourse.group/t/transitioning-from-mesh-xml-to-mesh-xdmf-from-dolfin-convert-to-meshio/412/17) for a full code snippet of how to do it with 3D meshes. (Small modifications needed for 2D: i.e. Tetra-\>triangle, triangle-\>line, dimension in meshvaluecollection 2-\>1)

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