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[comsol 3.5a electrostatic]too thin layer to create mesh

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Hello
I have developed 3D electrostatic model with 2 blocks (block A and block B), the distance between them is 0.1 mm. I must obtain capacitance so I draw a third block (block C) that surrounds them, block C simulates the vacuum environment. I have a problem creating the mesh, i suppose that the distance between A and B is so thin(0.1 mm) comparing to the blocks size that comsol isn't able to create the mesh. To avoid this problem i have tried to create vacuum environment only between A and B, creating a D block that stays in the space between A and B but i don't find electric field. The boundary conditions are :block A port 10V, block B port forced voltage 0 V or ground.what kind of condition Do i put on the block D to obtain the development of electric field in this space? Is it right this kind of model?
thank you
Luca

1 Reply Last Post Oct 5, 2009, 11:12 a.m. EDT
Ivar KJELBERG COMSOL Multiphysics(r) fan, retired, former "Senior Expert" at CSEM SA (CH)

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Posted: 2 decades ago Oct 5, 2009, 11:12 a.m. EDT
Hi Luca

from what you state it seems to be endeed purely a meshing problem so far. When I have very different scale sizes in my models, I make several sub-blocks, the interiour boundary often helps the mesher, if everything is rectangular its often easy. Sometimes I mesh mnually some edges in some regions.

Then I observethe results without the "equal" settings (double click on the square with the text "EQUAL" bottom frame of the graphics, then hit the rescale = 4 arrowas N,S,E,W,) in this way you see better what going on in the "thin" layers.

You have also manual meshing options to scale in a particular direction = usefull for rectagular shapes aligned with the coordinates.

there is more on the meshing in th doc, boundary layers in the AC/DC or RF module, different meshing approaches in the structural documentations

Hopes this helps a little
Good luck
Ivar
Hi Luca from what you state it seems to be endeed purely a meshing problem so far. When I have very different scale sizes in my models, I make several sub-blocks, the interiour boundary often helps the mesher, if everything is rectangular its often easy. Sometimes I mesh mnually some edges in some regions. Then I observethe results without the "equal" settings (double click on the square with the text "EQUAL" bottom frame of the graphics, then hit the rescale = 4 arrowas N,S,E,W,) in this way you see better what going on in the "thin" layers. You have also manual meshing options to scale in a particular direction = usefull for rectagular shapes aligned with the coordinates. there is more on the meshing in th doc, boundary layers in the AC/DC or RF module, different meshing approaches in the structural documentations Hopes this helps a little Good luck Ivar

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