[FLASH-USERS] ensuring div B = 0 when adjusting evolution

Fri May 26 16:51:30 EDT 2017

Hi Jon,

Have you tried refining on magx, magy, and magz, in addition to dens? I
have found this useful in the past for maintaining stability in MHD runs.
Other parameter values I have found useful for MHD runs are below.

Regards,
Jason

####################################################
refine_var_1    = "dens"
refine_var_2    = "magx"
refine_var_3    = "magy"
refine_var_4    = "magz"

eosModeInit = "dens_pres"
eosMode = "dens_pres"

slopeLimiter    = "hybrid"   # Slope limiters (minmod, mc, vanLeer [D],
hybrid, limited)
charLimiting    = .true. # Characteristic limiting vs. Primitive limiting

use_flattening    = .true. # use flattening (dissipative) (originally for
PPM)
use_cma_flattening = .true. # use flattening on mass fractions (originally
for PPM)
use_cma_advection = .true.

#       II. MAGNETIC(B) AND ELECTRIC(E) FIELDS:
E_modification  = .true.           # High order algorithm for E-field
construction
energyFix       = .true.           # Update magnetic energy using staggered
B-fields
prolMethod      = "BALSARA_PROL" # Prolongation method (injecton_prol,
balsara_prol)

#    III. RIEMANN SOLVERS:
RiemannSolver    = "HLLD"

######################################################

----
Jason Galyardt
Department of Physics and Astronomy
University of Georgia

On Fri, May 26, 2017 at 4:38 PM, Slavin, Jonathan <jslavin at cfa.harvard.edu>
wrote:

> To answer Sean and Ernesto's questions:
> I am using the USM solver and AMR.  I have now determined that div B is
> still 0 after the second explosion, which is not too surprising since, for
> this run, I have not changed the magnetic field and include div B cleaning
> (killdivb = .true.). So the problem is not with non-zero div B but with the
> large B fluctuations that are initiated. I noticed that there are small
> scale fluctuations in the region where the second explosion is initiated
> before the explosion, though the field is weak ~ 0.01 muG.  The
> fluctuations after the explosion go from ~ -1000 muG - +1000 muG.  I do
> expect amplification of B field fluctuations at the shock, but not to that
> extent.
>
> The way I'm initiating the second explosion is (almost) the same way I
> initiate the first one - I set the pressure of parcels within a given
> radius to a value such that the sum of the energy in those parcels is equal
> to the value I want for the explosion (1.E51 ergs).  I set the density to a
> value so as to have the mass total to 8 solar masses.  So all the energy is
> thermal at first.  I'll see about calling the EOS unit, since I haven't
> done that.  Any additional info on how to do that would be appreciated.
>
> Thanks,
> Jon
>
> On Fri, May 26, 2017 at 1:00 PM, <flash-users-request at flash.uchicago.edu>
> wrote:
>>
>> ---------- Forwarded message ----------
>> From: ERNESTO ZURBRIGGEN <ezurbriggen at unc.edu.ar>
>> To: flash-users at flash.uchicago.edu
>> Cc:
>> Bcc:
>> Date: Fri, 26 May 2017 10:56:45 -0300
>> Subject: Re: [FLASH-USERS] ensuring div B = 0 when adjusting evolution
>> Hi Jon!
>>
>> Have you tried to set off a less intense second supernova explosion? Have
>> you observed the same problems in that case? The second explotion might be
>> much too intense.
>>
>> On the other hand, how do you set the later explotion? I mean, applying
>> the explotion, are you consistently modifying the thermodynamical
>> variables? For example, if you instantaneously modify the density and the
>> temperature, then you also should call the Eos unit to keep the
>> consistence. I have experimented situations in which just modifying
>> velocities and keeping the thermodynamics unaltered, I also had to call the
>> Eos unit in order to maintain consistence
>>
>> Some runtime parameter that might help being on are 'shockDetect' and
>> 'shockLowerCFL' (this last one I think is just in realease 4.4).
>>
>>
>> Best!
>>
>> --
>> *Ernesto Zurbriggen*
>>
>> *Instituto de Astronomía Teórica y Experimental (IATE). *
>> *Observatorio Astronómico de Córdoba (OAC), **Universidad Nacional de
>> Córdoba **(UNC)**. *
>> *Teléfono: +54 0351 4331064-5, interno 222. *
>> *Córdoba, Argentina.*
>>
>>
>> ---------- Forwarded message ----------
>> From: "Sean M. Couch" <couch at pa.msu.edu>
>> To: "Slavin, Jonathan" <jslavin at cfa.harvard.edu>, flash-users <
>> flash-users at flash.uchicago.edu>
>> Cc:
>> Bcc:
>> Date: Fri, 26 May 2017 14:07:22 +0000
>> Subject: Re: [FLASH-USERS] ensuring div B = 0 when adjusting evolution
>> Hi Jon,
>>
>> Can you give a little more info? Are you using the USM solver? Are you
>> using AMR? Have you actually checked that divB>0 in the output data? A log
>> file from a representative run would be useful.
>>
>> In my experience, the USM solver in cylindrical R-Z coordinates with AMR
>> can be….touchy. But it should work and maintain divB=0! (See, e.g.,
>> http://adsabs.harvard.edu/cgi-bin/nph-data_query?bibco
>> de=2013ApJ...773..136J&link_type=EJOURNAL).
>>
>> Cheers,
>> Sean
>>
>>
>> ------------------------------------------------------------
>> ----------------------------------------------
>> Sean M. Couch
>> Assistant Professor
>> Department of Physics and Astronomy
>> Department of Computational Mathematics, Science, and Engineering
>> National Superconducting Cyclotron Laboratory/Facility for Rare Isotope
>> Beams
>> Michigan State University
>> 567 Wilson Rd, 3250 BPS
>> East Lansing, MI  48824
>> (517) 884-5035    ——    couch at pa.msu.edu    ——    www.pa.msu.edu/~couch
>>
>>
>>
>>
>> On May 25, 2017 at 4:41:45 PM, Slavin, Jonathan (jslavin at cfa.harvard.edu)
>> wrote:
>>
>> Hi all,
>>
>> I'm running MHD simulations where I set off a second supernova explosion
>> within a pre-existing remnant.  I'm using Simulation_adjustEvolution for
>> this.  However, I'm running into a problem with the magnetic field just
>> after initiating the second explosion.  I'm getting very large
>> pixel-to-pixel variations in Bx and By at the edge of the new expanding
>> blast wave.  I'm thinking that it could be because of non-zero div B in the
>> region in which the explosion is generated. So my question is, does anyone
>> have a suggestion for div B cleaning at the point that the explosion is
>> started, i.e. within Simulation_adjustEvolution, to prevent the problems
>> I'm having? I don't really expect the B field to be dynamically important
>> inside the remnant (beta >> 1), so accuracy of the B field is probably not
>> important there.  I should add that I'm doing these calculations in 2D
>> cylindrical symmetry (R-Z).  Thanks in advance for any help.
>>
>> Regards,
>> Jon
>>
>>
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>>
> --
> ________________________________________________________
> Jonathan D. Slavin                 Harvard-Smithsonian CfA
> jslavin at cfa.harvard.edu       60 Garden Street, MS 83
> phone: (617) 496-7981       Cambridge, MA 02138-1516
> cell: (781) 363-0035             USA
> ________________________________________________________
>
>
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