[FLASH-USERS] 1. Unit system issues 2. Output new quantities in the checkpoint file

[Hansen, Eddie]

Yes, FLASH’s default units are a scaled CGS system, so velocities in cm/s, pressure in barye, etc.

The code already does the proper unit conversion for SESAME tables, so there’s no need to convert table values prior to using it; just use the table as-is from the sesame library.

If you’re using the implicit resistivity solver, then ohmic heating will be stored in a variable named ‘qohm’ if add this line to your simulation’s Config file:
VARIABLE qohm

If you’re solving resistivity explicitly, then you’d still have to add that line to Config, but then also add lines of code to store it. It’s calculated in  hy_uhd_getFaceFlux.F90, but it’s just not stored in the UNK array.

--
Eddie Hansen
Applications Group Leader
Flash Center for Computational Science


From: flash-users <flash-users-bounces at flash.rochester.edu> on behalf of lizy <3287940670 at qq.com>
Date: Wednesday, July 30, 2025 at 12:05 AM
To: flash-users <flash-users at flash.rochester.edu>
Subject: [FLASH-USERS] 1. Unit system issues 2. Output new quantities in the checkpoint file
Dear Flash developers,
1. Except electromagnetic quantities such as magnetic fields and currents, are all other data output by flash, such as pressure and velocity, using Gaussian units?
2. If that's the case, I imported the SESAME equation of state table. Is it true that the units for temperature, density, and pressure should also use Gaussian units?
3. Joule heating Q is not in the output file of the checkpoint file. Where should I declare this quantity and make it output?
Thank you very much for your response amidst your busy schedule.
Best wishes!
Lizy
7/30  2025
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