[FLASH-USERS] unit system in Zpinch model

[Reyes, Adam]

I assume you’re referring to this document <https://flash.rochester.edu/pipermail/flash-users/attachments/20121001/020d8ee4/attachment.pdf> on unit systems in FLASH?

I would not recommend setting the unit system in FLASH and instead use unitSystem=“none”, which is the default behavior. Other choices, while potentially convenient, make it rather difficult to reason about what units are being used where in the code and I’m not confident the usage is 100% correct everywhere.

The Zpinch problem as provided uses FLASH’s “none” units. In this case the MagneticResistivity unit will calculate the resistivity as cm^2/s as you said. To go from resistivity in MKS to FLASH units you would do \eta_{FLASH} = \eta_{ohms*m}/\mu_0. This is the right most column in Table 6.
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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)


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> On May 22, 2024, at 9:34 AM, lizy <3287940670 at qq.com> wrote:
> 
> Dear Flash developers and engineers
>     The magnetic resistances used in Flash include Spitzer HighZ resistance and DaviesWen resistance types.
>     1. What is their unit in the zpinch case, is it cm ^ 2 · s ^ (-1)? I have resistivity calculated by other software here (in ohms · meters) and would like to import it into the zpinch     model. What parameter should I multiply my calculated resistivity by?
>     2. I have read the help document, but still have doubts about the unit system used by zpinch. Unless otherwise specified, should the Gaussian unit system be used by default.     For example, in the zpinch case, what is the unit of current density?
>                                                                                                                              Thank you very much for your reply amidst your busy schedule    
>                                                                                                                                                                                                                                                                lizy                                                                                                     
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