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Mesh question [simple]

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Hello,

I think I've got a simple question:

I drawed a 3 dimensional T-junction (fluid dynamics, navier-stokes). Started in 2D and choosed Draw>Specify Objects>line... and extruded my 2 dimensional T-junction [Closed Polyline (solid)] to a 3 dimensional T-junction.
The height and the width of the channels are 1.1e-3m the channel length of the horizontal part of the 'T' (two inlets) is in total 0.66m and the length of the vertical part is 1,64m.
So, very narrow channels with respect to the length.

The problem is that an error occurs while creating a mesh.

Error: 4100
Failed to generate mesh for subdomain.
- Subdomain: 1
Failed to respect boundary element edge on geometry face.
- Face: 4
- x coordinate: 0
- y coordinate: 0.466025
- z coordinate: 0.0011
Internal error in boundary respecting.

Does the error occure due to the size/shape of the T-junction? To narrow with respect to it's length?
After scaling x and y by 0.1 remeshing is no problem.

Thanks for your time!
Greetings, Mark.

2 Replies Last Post 01.03.2010, 03:52 GMT-5

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Posted: 1 decade ago 26.02.2010, 07:20 GMT-5
Decreasing the mesh from normal to coarse makes remeshing also possible, but the problem with the decreasing mesh is that my mesh is to coarse for my problem.
Decreasing the mesh from normal to coarse makes remeshing also possible, but the problem with the decreasing mesh is that my mesh is to coarse for my problem.

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Posted: 1 decade ago 01.03.2010, 03:52 GMT-5
I've made some progress since my last post.
I devided the T-junction in 11 parts with some extra interior boundaries.
Now I can make a much finer mesh, but the pressure drop increases with a decreasing (maximum)mesh-size.
That could be possible when the mesh is to coarse, but I think the mesh-size I use now is fine enough.

The simulated value for the pressure drop is roughly 1400 Pa with the following mesh parameters:
maximum mesh element size: 0.001
maximum element solving factor: 0.2
element growth rate: 1.1
Mesh curvature factor: 0.2
Mesh curvature cutoff: 0.005
Resolution of narrow regions: 0.9

My channel size is 1.1e-3 m * 1.1e-3 m.

Any ideas why the simulated pressure drop value is strongly dependant on the mesh-size I use?

Thanks a lot!

Greetings,
Mark van Gerven.
I've made some progress since my last post. I devided the T-junction in 11 parts with some extra interior boundaries. Now I can make a much finer mesh, but the pressure drop increases with a decreasing (maximum)mesh-size. That could be possible when the mesh is to coarse, but I think the mesh-size I use now is fine enough. The simulated value for the pressure drop is roughly 1400 Pa with the following mesh parameters: maximum mesh element size: 0.001 maximum element solving factor: 0.2 element growth rate: 1.1 Mesh curvature factor: 0.2 Mesh curvature cutoff: 0.005 Resolution of narrow regions: 0.9 My channel size is 1.1e-3 m * 1.1e-3 m. Any ideas why the simulated pressure drop value is strongly dependant on the mesh-size I use? Thanks a lot! Greetings, Mark van Gerven.

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