[FLASH-USERS] Checkboard of Magnetic Monopoles

[dongwook at flash.uchicago.edu]

Hi Aaron,

I'd like to ask you a couple of questions in order to understand the issue
better. More questions wil follow in the subsequent emails replying to
your other emails.

(1) What is the grid geometry you're using? I understand that you're
interested in working on cylindrical implementation at some point and I
wonder if you are seeing these monopoles on your own cylindrical
implementation or not. Is this any non-Cartesian implementation?

(2) What is the dimension of the problem? Is it 2D?

Best,
Dongwook

=========================================
Dongwook Lee, Ph.D., Research Scientist
The Flash Center for Computational Science
The University of Chicago
5747 S. Ellis Ave., Room 319
Chicago, IL 60637
(773) 834-6830

> I am using the USM MHD solver with flash3 and I noticed that I am getting
> very large magnetic monopoles appearing in my solution, of the same order
> as the magnetic fields.  The monopoles appear in a somewhat random
> checkboard-like pattern, which I believe has something to do with the
> block-structure of the mesh.  I have attached two plots which show the
> magnitude of divb and posted copies online in case the mailing list does
> not allow file attachments.
>
> Cylindrical Shell Compression 2D - abs(divb)
> http://oi40.tinypic.com/1zeihbp.jpg
>
> Spherical Shell Compression 3D - abs(divb)
> http://oi39.tinypic.com/34grldv.jpg
>
> The central circle where the checkboard pattern appears is the only volume
> that is magnetized.  I am using a static AMR mesh with a uniform
> resolution across the magnetized volume, and less refinement in the
> surrounding non-magnetized fluid.  Has anyone observed similar behaviour?
> It is definitely numerical in nature, but I do not know what part of the
> code is responsible.
>
> Thanks,
> Aaron