[FLASH-USERS] questions about 1. Unit system 2. Adding additional types of substances

[Hansen, Eddie]

For Z-pinch problems to work properly with the rest of FLASH, you should not change the unit system from its default value. There are certain material properties and MHD routines in FLASH that assume the default unit system.

So the units in the output are (mostly) CGS. B-fields are scaled by a factor of sqrt(4 pi), so you multiply an output variable like 'magx' by this factor to get G. Current is tricker. If you're talking about a 'circuit.dat' output file, then the units should be A. If you're referring to current densities like 'cury' in the output, then you have to multiply by 10^5 / sqrt(4 pi) to get A/m^2.

For the species, you first have to add them to the species=fill,line,vacu list inside the setup command, and they cannot be longer than 4 characters.


--

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: Sunday, June 29, 2025 at 10:13 PM
To: flash-users <flash-users at flash.rochester.edu>
Subject: [FLASH-USERS] questions about 1. Unit system 2. Adding additional types of substances

Dear Flash developers and users,
I have two questions about zpinch simulation and hope to receive your answers.
1.In the zpinch case, the units of output data, such as current in A/m2 and speed in cm/s, are they correct?
2.In the 'Simulation_initblock' file, I added substances other than 'fill, line, vacu', such as' line1, line2, line3 ', and defined them in the flash. par file, but why is there only the mass percentage of' fill, line, vacu 'in the output file? (For example, It is supposed to output the quality scores for "fill, line, vacu, line1, line2, line3",but the result is "fill, line, vacu, line, line,line")
Thank you very much for your answers.
lizy
6.30.2025
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