# Unpaired faces in mesh, error

**URL:** <https://pyfr.discourse.group/t/unpaired-faces-in-mesh-error/174>\
**Category:** General\
**Created:** [9 September 2017 13:05 UTC](https://pyfr.discourse.group/t/unpaired-faces-in-mesh-error/174 "2017-09-09T13:05:32Z")\
**Posts on this page:** 2\
**Page:** 1

<div class="post-metadata">

**Author:** ![Ezhilmathi\_Krishnasa](https://avatars.discourse-cdn.com/v4/letter/e/f4b2a3/32.png) [@Ezhilmathi\_Krishnasa](https://pyfr.discourse.group/u/Ezhilmathi_Krishnasa)\
**Post date:** [9 September 2017 13:05 UTC](https://pyfr.discourse.group/t/unpaired-faces-in-mesh-error/174/1 "2017-09-09T13:05:32Z")

</div>

Hi,

I am getting an error for the mesh conversion of simple 3D model (sphere in the fluid domain)

`(root) tegner-login-1$ pyfr import -t gmsh sphere1.msh sphere.pyfrm`

```auto
Traceback (most recent call last):
File "/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/bin/pyfr", line 11, in <module>
load_entry_point('pyfr==1.7.0', 'console_scripts', 'pyfr')()
File "/afs/pdc.kth.se/roots/srv/tegner/v1.8/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/lib/python3.6/site-packages/pyfr-1.7.0-py3.6.egg/pyfr/ __main__.py", line 110, in main
File "/afs/pdc.kth.se/roots/srv/tegner/v1.8/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/lib/python3.6/site-packages/pyfr-1.7.0-py3.6.egg/pyfr/ __main__.py", line 124, in process_import
File "/afs/pdc.kth.se/roots/srv/tegner/v1.8/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/lib/python3.6/site-packages/pyfr-1.7.0-py3.6.egg/pyfr/readers/base.py", line 23, in to_pyfrm
File "/afs/pdc.kth.se/roots/srv/tegner/v1.8/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/lib/python3.6/site-packages/pyfr-1.7.0-py3.6.egg/pyfr/readers/gmsh.py", line 200, in _to_raw_pyfrm
File "/afs/pdc.kth.se/roots/srv/tegner/v1.8/cfs/klemming/nobackup/k/kriezh/ANACONDA_TEGNER/lib/python3.6/site-packages/pyfr-1.7.0-py3.6.egg/pyfr/readers/base.py", line 194, in get_connectivity
ValueError: Unpaired faces in mesh

```

I guess, am making some mistake in gmsh, but it looks OK to me, could some one take a  
quick look and let me know where I am making mistake.

Kind regards,  
Mathi

[sphere1.geo](https://pyfr.discourse.group/uploads/short-url/jDnF7JFrQXeBhYM8AMJEZgoaPce.geo) (2.48 KB)

[sphere1.msh](https://pyfr.discourse.group/uploads/short-url/4xic87qKGxg1BPPAvCNP0VndCIx.msh) (2.27 MB)

---

<div class="post-metadata">

**Author:** ![nnunn](https://avatars.discourse-cdn.com/v4/letter/n/c89c15/32.png) [@nnunn](https://pyfr.discourse.group/u/nnunn)\
**Post date:** [19 September 2017 06:19 UTC](https://pyfr.discourse.group/t/unpaired-faces-in-mesh-error/174/2 "2017-09-19T06:19:56Z")

</div>

Hi Ezhilmathi,

The mesh is not getting the sphere boundary faces defined as a “physical” surface.  
But it seems to work if you change your line for Physical Surface(“sphere”) = …

// Surface loop for volume definition  
Surface Loop(29) = {14, 16, 18, 20, 22, 24, 26, 28};

// Physical Surface(“sphere”) = {29}; // old version

Physical Surface(“sphere”) = {14, 16, 18, 20, 22, 24, 26, 28}; // \<= try this

Nigel