[FLASH-USERS] ​Add the resistivity η to the simulation of magnetoHD

[zdy0903]

Hi all！

 

I met some problems when trying to add the resistivity η to the simulation of magnetoHD/NohCylindrical(user manual 32.2.4),

 

First, the units of resistivity troubles me. In the CGS UnitSystem, whether setting resistivity = 1 in “flash.par” means set magnetic resistivity η=1 cm2/s=10-11 Ω·m and magnetic viscosity υm=η·c·c/(4·pi), where c=3·1010 cm/s?

 

Second, the calculation about resistivity troubles me. Looking through the kernels and helpers of Diffuse Unit, I can’t find any calculation about resistivity. Is it in the kernels and helpers of Hydro Unit? I can’t find the calculation about magnetic diffusion in the Hydro Unit. Is it needed to REQUIRE Diffuse?

 

Finally, When I set these parameter in “flash.par” as below and setup with +usm

#     Units (none, SI or CGS)

UnitSystem        = "CGS"

##    Resistive MHD parameters     ##

useDiffuse    = .true.

 dt_diff_factor  = 0.8

useMagneticResistivity     = .true.

 resistivity          = 0.0 # magnetic Resistivity

mpirun stopped with the same message, even if setting a large range of resistivity, from 1020 to 10-40

      DRIVER_ABORT: [Hydro]: Computed dt is not positive! Aborting!

      dtCheck=   0.0000000000000000




How to solve these problem? Really need someone to help!

 

Zhang


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