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Strange Effect with Dirichlet BC

Posted May 21, 2011, 5:26 p.m. EDT Geometry, Studies & Solvers Version 4.1 2 Replies

cchriste
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I using the general form PDE to model a system. The geometry is very simple, just a single rectangle, with a Dirichlet condition on one sides (I add more physics in the full simulation but can reproduce these effects without other physics).

Everything works fine unless I add two smaller rectangles adjacent to the main rectangle on the side with BC. When I do this, the solution becomes non-physical and much different than without these smaller rectangles. I do not have even have to apply the PDE physics to these new domains to get this effect. If I add a small "buffer" layer between the small rectangles and the main one, the effect goes away, but this will affect the other physics of the model that I have to add later.

Does anyone know why this could be happening? Thanks.
2 Replies Last Post May 22, 2011, 5:06 p.m. EDT
Joonas Mäkinen
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Posted: 1 decade ago May 22, 2011, 11:46 a.m. EDT
Hard to say anything without seeing the model itself. Could you attach it?
Hard to say anything without seeing the model itself. Could you attach it?
cchriste
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Posted: 1 decade ago May 22, 2011, 5:06 p.m. EDT
I actually figured it out. I was trying to reproduce the results from the ground up to give you a cleaner example, and discovered it was the mesh. When adding the rectangles, the boundary becomes segmented, which changes the way I had to implement the mapped mesh. You can see the two examples below (mesh1 is wrong, mesh2 is right). The quantity u1 should be constant throughout the domain.
I actually figured it out. I was trying to reproduce the results from the ground up to give you a cleaner example, and discovered it was the mesh. When adding the rectangles, the boundary becomes segmented, which changes the way I had to implement the mapped mesh. You can see the two examples below (mesh1 is wrong, mesh2 is right). The quantity u1 should be constant throughout the domain.

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