mesh warning

Saman95 · May 20, 2019, 09:05

hello dear

I want to solve a problem with ansys fluent in the axisymmetric mode, but i when i check the mesh a warning as following is showed in console:

{
Domain Extents: x-coordinate: min (m) = 0.000000e+00, max (m) = 3.000000e-01
y-coordinate: min (m) = -7.485200e-05, max (m) = 2.000000e-03
Volume statistics:
minimum volume (m3): 1.736124e-08
maximum volume (m3): 5.793137e-08
total volume (m3): 3.767267e-06
minimum 2d volume (m3): 5.775142e-06
maximum 2d volume (m3): 6.224858e-06
Face area statistics:
minimum face area (m2): 9.625237e-04
maximum face area (m2): 6.000007e-03
Checking mesh..............
WARNING: Invalid axisymmetric mesh with nodes lying below the x-axis.............
Done.

WARNING: Mesh check failed.

To get more detailed information about the mesh check failure
increase the mesh check verbosity via the TUI command
/mesh/check-verbosity.
Fluent can also try to fix the mesh check problems via the TUI command
/mesh/repair-improve/repair.
}

does anyone know about this?

LuckyTran · May 20, 2019, 12:19

It's a meshing problem. You need to go back to your mesh generator and figure out what you did wrong.

In Fluent, the axis for axisymmetric problems is always the y=0 axis and you generate a mesh on the upper XY plane (the y > 0 half-plane).

Your mesh generation software doesn't know this. It just makes a mesh based on your inputs and even if you import CAD that you think is a box on the upper half plane, you can end up with a mesh with some nodes that end up in the negative y areas for various reasons.

It's a combination of importing the right geometry/CAD and specifying the right mesh settings.

A workaround might be to translate your mesh upwards by a tiny amount such that all the cells are now strictly y>0. Do this at your own risk. The difference of a few micrometers is usually not that significant.

May 20, 2019, 09:05	mesh warning	#1
Saman95 Member Join Date: Nov 2017 Posts: 54 Rep Power: 8	hello dear I want to solve a problem with ansys fluent in the axisymmetric mode, but i when i check the mesh a warning as following is showed in console: { Domain Extents: x-coordinate: min (m) = 0.000000e+00, max (m) = 3.000000e-01 y-coordinate: min (m) = -7.485200e-05, max (m) = 2.000000e-03 Volume statistics: minimum volume (m3): 1.736124e-08 maximum volume (m3): 5.793137e-08 total volume (m3): 3.767267e-06 minimum 2d volume (m3): 5.775142e-06 maximum 2d volume (m3): 6.224858e-06 Face area statistics: minimum face area (m2): 9.625237e-04 maximum face area (m2): 6.000007e-03 Checking mesh.............. WARNING: Invalid axisymmetric mesh with nodes lying below the x-axis............. Done. WARNING: Mesh check failed. To get more detailed information about the mesh check failure increase the mesh check verbosity via the TUI command /mesh/check-verbosity. Fluent can also try to fix the mesh check problems via the TUI command /mesh/repair-improve/repair. } does anyone know about this?

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May 20, 2019, 12:19		#2
LuckyTran Senior Member Lucky Join Date: Apr 2011 Location: Orlando, FL USA Posts: 5,673 Rep Power: 65	It's a meshing problem. You need to go back to your mesh generator and figure out what you did wrong. In Fluent, the axis for axisymmetric problems is always the y=0 axis and you generate a mesh on the upper XY plane (the y > 0 half-plane). Your mesh generation software doesn't know this. It just makes a mesh based on your inputs and even if you import CAD that you think is a box on the upper half plane, you can end up with a mesh with some nodes that end up in the negative y areas for various reasons. It's a combination of importing the right geometry/CAD and specifying the right mesh settings. A workaround might be to translate your mesh upwards by a tiny amount such that all the cells are now strictly y>0. Do this at your own risk. The difference of a few micrometers is usually not that significant.