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

[王东升]

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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