[FLASH-USERS] NohCylindrical problem - different results using different FLASH versions

[Reyes, Adam]

Hi Jiri,

There is indeed something wrong with this problem in 4.7.1. There is another variant of the problem that exists in “magnetoHD/unitTest/NohCylindricalRagelike”. You should be able to set it up exactly the same otherwise and use the same parfile. When I try it this way I don’t see the oscillations. I’m not sure what is so different about these two setups, but the “NohCylindricalRagelike” is used in our nightly unit testing and does seem to still be working.
*********************************************
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)


*********************************************



> On Oct 4, 2023, at 7:44 PM, Loffelmann, Jiri <loffejir at fjfi.cvut.cz> wrote:
> 
> Hello FLASH users,
> 
> I ran the problem magnetoHD/NohCylindrical (Magnetized Noh Z-pinch) that is provided with the code (version 4.7.1) and I got a weird result, a bit different from Figure 34.50 in the PDF guide. In this result, one can see some oscillations that are created at the top and bottom of the computational interval.
> When I run the same problem with FLASH code version 4.6.2, I get the same result as is presented in the guide (Figure 34.50), without these oscillations.
> When run with version 4.7, the result is the same as with version 4.7.1 (with oscillations).
> 
> From this, I conclude that there is some kind of bug in the new versions of the code. But I have no idea what it could be...
> When I increase the resolution, the frequency of the oscillations also increases.
> I did not notice this in other simulations, probably when using mag. diffusion, these oscillations are negligible?
> 
> Here is a detailed description of the performed simulations:
> I performed simulations using different meshes and different values of conserveAngField (no specific reason, just noticed it also does something..).
> I have attached the results figures with corresponding names.
> Simulations use provided .par files (some with described modifications).
> 
> version FLASH4.6.2:
> 1] data_4.6.2_amr
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm
> mpirun -np 4 ./flash4
> flash.par  unchanged
> 
> 2] data_4.6.2_ug
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm +ug -nxb=128 -nyb=128
> mpirun -np 4 ./flash4
> flash.par  unchanged
> 
> 3] data_4.6.2_ug_2
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm +ug -nxb=128 -nyb=128
> mpirun -np 4 ./flash4
> flash.par  changed: added line "conserveAndField=.true."
> 
> version FLASH4.7.1:
> 1] data_4.7.1_amr
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm
> mpirun -np 4 ./flash4
> flash.par  changed: added line "useMagneticResistivity=.false." (in the new version, the default was changed to .true.)
> 
> 2] data_4.7.1_ug
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm +ug -nxb=128 -nyb=128
> mpirun -np 4 ./flash4
> flash.par  changed: added line "useMagneticResistivity=.false." 
> 
> 3] data_4.7.1_ug_2
> ./setup -auto magnetoHD/NohCylindrical -2d +cylindrical +hdf5typeio +usm +ug -nxb=128 -nyb=128
> mpirun -np 4 ./flash4
> flash.par  changed: added lines "useMagneticResistivity=.false.", "conserveAndField=.true."
> 
> Do you have any tips, on what it could be?
> 
> Regards,
> Jiří Löffelmann
> 
> <data_4.6.2_ug_2.png><data_4.6.2_ug.png><data_4.6.2_amr.png><data_4.7.1_ug_2.png><data_4.7.1_ug.png><data_4.7.1_amr.png>_______________________________________________
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