[FLASH-USERS] Diffusion problem of angular magnetic field in one dimension

[Adam Reyes]

Hi Wang,

This revealed a small bug in the HYPRE solver for this problem. I'm
attaching a patch here.

You can copy it to the "FLASH4.7" directory and apply it with

> path -p1 < MagDiff.patch


Thanks for reporting the issue!

*************************************************************************
Adam Reyes

Code Group Leader, Flash Center for Computational Science
Research Scientist, Dept. of Physics and Astronomy
University of Rochester
River Campus: Bausch and Lomb Hall, 369
500 Wilson Blvd. PO Box 270171, Rochester, NY 14627
Email adam.reyes at rochester.edu
Web https://flash.rochester.edu
 (he / him / his)

*************************************************************************

On Fri, Apr 28, 2023 at 6:58 AM 王东升 <wangdswork at stu.xjtu.edu.cn> wrote:

> Hello Eddie,
> Thank you very much for your reply.
> I have checked the drawing of species variables (fill, line, vacu) and
> they were all still present in the simulation process. The resistivity of
> the vacuum has also been checked which remained 1e9(cm2/s) in the vacuum
> region.
> In fact, I didn’t make a lot of changes with Z-Pinch file. Here are some
> of the changes I've made:
> 1. I set the fluid velocity to zero in the
> "Simulation_adjustEvolution.F90" file to rule out the magnetic freezing
> effect.
> 2. The current was set to 1MA in the "current.bat" file.
> 3. The thermal conductivity and radiation transport module was set to
> false in the "flash.par" file.
> 4. The density of liner was set to 3e-3(g/cm3) as the plasma region, and
> the vacuum resistivity was set to 1e9(cm2/s).
> 5. I set 0 to 0.8cm for species "line" as the plasma region and 0.8 to 1cm
> for species "vacu" as the vacuum region in the "Simulation_initBlock.F90"
> file.
> I attached the image of the species variable and the resistivity, and I
> also attached the "flash.par".
> Thank you again and look forward to your reply.
> Best wishes,
> Wang
>
>
> 在 2023-04-28 03:04:33，"Hansen, Eddie" <ehansen at pas.rochester.edu> 写道：
>
> >Hi Wang,
> >
> >
> >
> >Have you plotted the species variables (fill, line, vacu) to make sure
> you still have vacuum in the domain? It would also be good to check the
> resistivity (res2).
> >
> >
> >
> >It’s hard to tell what might be going wrong without more info. Can you
> send the par file?
> >
> >
> >
> >--
> >
> >Eddie Hansen
> >
> >Research Scientist
> >
> >Flash Center for Computational Science
> >
> >
> >
> >
> >
> >From: flash-users <flash-users-bounces at flash.rochester.edu> on behalf of
> 王东升 <wangdswork at stu.xjtu.edu.cn>
> >Date: Thursday, April 27, 2023 at 1:19 PM
> >To: flash-users <flash-users at flash.rochester.edu>
> >Subject: [FLASH-USERS] Diffusion problem of angular magnetic field in one
> dimension
> >
> >Dear FLASH user & developers,
> >    I have a question about implicit magnetic diffusion in FLASH4.7. I
> wanted to observe the diffusion of angular magnetic field in one dimension,
> so I set the fluid velocity to zero in the "Simulation_adjustEvolution.F90"
> file to rule out the magnetic freezing effect. However, I found that the
> magnetic field diffused slowly in vacuum, which is quite different from the
> result of a paper I saw. I have attached the comparison diagram of the two
> results.
> >    The vacuum resistivity I set is 1e9(cm2/s), and the vacuum region is
> between 0.8 and 1cm. I modified it on the Z-Pinch file, and the current was
> set to 1MA.
> >    I would appreciate any help.
> >    Thanks!
> >Best,
> >Wang Dongsheng
> _______________________________________________
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>
> For list info, including unsubscribe:
> https://flash.rochester.edu/mailman/listinfo/flash-users
>
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