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Thermal PDE in cylindrical coordinates at the origin

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I have a problem with a thermal PDE in cylindrical coordinates. I followed the example in Heat Distribution in Circular Cylindrical Rod .
The script runs without errors, however the solution has peculiar spot at z = 0, r = 0 where the Temperature is constantly zero. The heat source at that spot is well larger than zero and all around the spot a temperature which is as expected is reached.
I tried changing several of the pde SolverOptions or choose the mesh differently, however nothing of what I tried was successful.
Does anybody have an idea what I can do to fix this issue?
Thanks in advance

Accepted Answer

Tobias on 29 Jul 2019
My error was in not transforming the boundary condition correctly. I had assumed that the BC in the example just had a curios form, but the *region.y originated from the transfer to cylindrical coordinates.
With the correct BC the solution makes sense on the whole domain.

More Answers (2)

Svetlana Pease
Svetlana Pease on 11 Jan 2019
Hi Tobias,
Are you talking about the steady-state or transient solution? The only zero temperature I get is for the transient solution at t = 0 (time step is 1 for t = 0).
Svetlana Pease
MathWorks Documentation Group
Tobias on 18 Jan 2019
Is there a possibility to create the mesh with two different Hmax? I naively tried to assembly the mesh in two steps but I was not allowed to change the read-only FEMesh.
If I calculate my problem in full 3d the problem does not appear (however I cannot choose my grid fine enough to get rid of other oscillations)
Torsten on 18 Jan 2019
I'd simply start with the geometry at r = eps instead of r = 0 for eps being a small value.

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Svetlana Pease
Svetlana Pease on 18 Jan 2019
Hi Tobias,
No, there is no option to have two or more Hmax settings for the same geometry/mesh.




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