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-   -   [ICEM] How to Mesh around cylinders very close to a wall (https://www.cfd-online.com/Forums/ansys-meshing/235137-how-mesh-around-cylinders-very-close-wall.html)

sameedakber April 2, 2021 21:25

How to Mesh around cylinders very close to a wall
 
2 Attachment(s)
Hi Everyone. This is my first post. I'm sorry in advance if there is an error in my post formatting.

I'm simulating flow in an open channel as it flow past cylinders arranged in a pattern. Normally, for flow past a cylinder, I would use an O-grid meshing (around said cylinder) but I'm struggling to find a meshing method for the case where cylinder is very close to the boundary (walls). I've managed to generate a mesh in ICEM but it seems to be faulty when I feed it into Fluent.

Could anyone point me in the right direction as to how an appropriate meshing could be generated in this case in ICEM CFD. Thank you. I've attached my geometry and mesh (faulty).

aero_head April 2, 2021 22:39

So what is wrong with the mesh, is it giving you bad quality elements?
Maybe the readout of the quality/min. angle of elements would be useful to include. I can imagine there might be bad quality elements where the wall meets the cylinder.

You might have to manually adjust the vertices to increase the angle.

sameedakber April 3, 2021 10:35

Quote:

Originally Posted by aero_head (Post 800557)
So what is wrong with the mesh, is it giving you bad quality elements?
Maybe the readout of the quality/min. angle of elements would be useful to include. I can imagine there might be bad quality elements where the wall meets the cylinder.

You might have to manually adjust the vertices to increase the angle.

Thanks for the reply. ICEM says the mesh has 'negative elements'. Could you please elaborate what you meant by manually adjusting the vertices. Thanks

JBeilke April 3, 2021 10:54

1 Attachment(s)
It is the worst type of geometry to mesh, because your domain runs into a very small angle. Just cheat a little bit and let the cylinders slightly cross the wall.

sameedakber April 3, 2021 13:03

Quote:

Originally Posted by JBeilke (Post 800590)
It is the worst type of geometry to mesh, because your domain runs into a very small angle. Just cheat a little bit and let the cylinders slightly cross the wall.

Thank you. Meshing quality has improved when I let cylinders cross the wall slightly.

JBeilke April 3, 2021 16:20

2 Attachment(s)
A slightly better way is not to move the circle but to include 2 additional vertical lines.


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