[FLASH-USERS] Unit system

[Nathan Goldbaum]

Here's how yt handles this:

https://bitbucket.org/yt_analysis/yt/src/1088ca4ac8d84017d1809a6f114c852297286350/yt/frontends/flash/data_structures.py?at=yt&fileviewer=file-view-default#data_structures.py-239

If unitsystem is 'cgs', then magnetic field variables are written in Gauss
(no factors of 4pi). If unitsystem is 'none' (the default, I think?) then
you need to divide the values on-disk by sqrt(4*pi) to get gauss. If
unitsystem is 'si', then you need to divide by sqrt(4*pi/1e7).

Dongwook Lee summarized the situation when I asked about this in 2012,
including a nice pdf describing all the ins and outs. Take a look at his
message:

http://flash.uchicago.edu/pipermail/flash-users/2012-October/001180.html

On Wed, Mar 8, 2017 at 3:38 PM, Huynh Cong Tuan <huynhcongtuan7 at gmail.com>
wrote:

> Dear FLASH-USER,
> I have a little bit confusion about unit of magnetic field. For example, I
> run a simulation with the default unit system (cgs). The file
> flash_hdf5_plt_cnt_0001 contains variable magy (by). The value of by is 1.
> I am confusing about this value, in cgs, by=1 gauss or by=sqrt(4*pi) gauss?
> Thanks in advance.
> --
> Huynh Cong Tuan
>
>
>
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