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

[Ernesto Zurbriggen]

Hi Zhang!

>>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*?
The calculation of resistivity is made
in source/physics/materialProperties/MagneticResistivity/MagneticResistivityMain/Constant
(for constant resistivity).
Also, in your config file, have you included a require statament like
this?:
   REQUIRES
physics/materialProperties/MagneticResistivity/MagneticResistivityMain


Best!


El vie., 29 mar. 2019 a las 11:52, zdy0903 (<zdy0903 at stu.xjtu.edu.cn>)
escribió:

> 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
>
>

-- 
*Dr. Ernesto Zurbriggen*

**** Consejo Nacional de Investigaciones Científicas y Técnicas **(CONICET)**,
Instituto de Astronomía Teórica y Experimental (IATE), Argentina.*
**** Universidad Nacional de Córdoba **(UNC)**, **Observatorio Astronómico
de Córdoba **(OAC), Argentina**.*

*Teléfono: +54 0351 4331064-5, interno 222.*

*Laprida 854, Bº Observatorio (CP 5000), Córdoba, Argentina.*
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