[FLASH-USERS] Magnetic field boundary condition for NohCylindrical test problem

[Boyle, Gregory]

Hi Ernesto, 

Thank you very much for your advice! 

I would like to enforce a B_theta boundary condition, which should correspond to KAXIS and MAGZ_VAR as you suggested. This seems consistent with the output of the standard NohCylindrical test problem having only MAGZ_VAR be non-zero. 

I tested putting ivar == MAGX_VAR just in case, to no avail. I am now starting to suspect that, by using the unsplit staggered mesh, I perhaps need to enforce a condition on the cell faces. 

Any other advice or suggestions is much appreciated! 

Cheers, 
Greg. 



From: "Ernesto Zurbriggen" <ezurbriggen at unc.edu.ar> 
To: "flash-users" <flash-users at flash.uchicago.edu> 
Sent: Friday, 24 August, 2018 16:59:00 
Subject: Re: [FLASH-USERS] Magnetic field boundary condition for NohCylindrical test problem 

Hi Greg! 
I'm not in the details, but remember that in cylindrical geometry (IAXIS,JAXIS,KAXIS)=(r,z,theta). 

>>I am using the Unsplit Staggered Mesh MHD solver, and have included a modified Grid_bcApplyToRegion.F90 that alters the standard "reflect" condition on the HIGH face of IAXIS to: 
So, if you would like to modify the BC on the HIGH face of IAXIS, 

>> if(ivar == MAGZ_VAR) regionData(k-i,1:je,1:ke,ivar)= 1.0 
maybe you should put ivar == MAGX_VAR instead. 

Best! 

Ernesto 


El vie., 24 ago. 2018 a las 5:48, Boyle, Gregory (< [ mailto:gregory.boyle at desy.de | gregory.boyle at desy.de ] >) escribió: 


Dear FLASH community, 

I am attempting to modify the the 2D NohCylindrical test problem (32.2.4) to include a permanent B_{\theta} condition at rightmost r boundary. This is a first step towards including the effect of a longitudinal current. 

I am using the Unsplit Staggered Mesh MHD solver, and have included a modified Grid_bcApplyToRegion.F90 that alters the standard "reflect" condition on the HIGH face of IAXIS to: 

k = 2*guard+1 
if(isFace)k=k+1 
do i = 1,guard 
regionData(k-i,1:je,1:ke,ivar)= regionData(i,1:je,1:ke,ivar)*sign 
if(ivar == MAGZ_VAR) regionData(k-i,1:je,1:ke,ivar)= 1.0 
end do 

However, when I look at the output it seems the condition of setting MAGZ_VAR to 1.0 is being ignored. 

Any suggestions would be greatly appreciated! 

Cheers, 
Greg. 





-- 
Dr. Ernesto Zurbriggen 

Consejo Nacional de Investigaciones Científicas y Técnicas (CONICET) , Instituto de Astronomía Teórica y Experimental (IATE) . 

Universidad Nacional de Córdoba (UNC) , Observatorio Astronómico de Córdoba (OAC) . 

Teléfono: +54 0351 4331064-5, interno 222. 
Laprida 854, Bº Observatorio (CP 5000), Córdoba, Argentina . 

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