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-   -   MHD Shocktube test (https://www.cfd-online.com/Forums/openfoam-programming-development/162922-mhd-shocktube-test.html)

vedlk November 20, 2015 09:34

MHD Shocktube test
 
Hello, I have made a solver by merging the sonicFoam and mhdFoam.The B magnetic field density vector is coupled with rho to form compressible equation but the graph shows high oscillations and pressure and velocity graph is still the same,though I have added the magnetic terms in the equation. Can anybody explain me the reason behind these problems.:mad:

wyldckat November 22, 2015 08:11

Quote:

Originally Posted by vedlk (Post 574205)
Can anybody explain me the reason behind these problems.:mad:

Quick answer: I would actually like to try and explain this, but I can't figure out what exactly is going on from your description :(
Please follow the instructions given here: http://www.cfd-online.com/Forums/ope...-get-help.html

Quote:

Originally Posted by vedlk (Post 574205)
but the graph shows high oscillations and pressure and velocity graph is still the same

I can't figure out if the high oscillations graph is the B field or not, or if it's residuals... or whatever it is exactly :(

vedlk November 25, 2015 03:14

The graph is of B field. The pressure and velocity graphs are still the same as Euler's equations. I am asking what should I change ? Piso algorithm or something else

wyldckat November 28, 2015 13:24

Hi vedlk,

I've taken a look into the two solvers and it is indeed possible that you might have confused something in the merger of the two solvers.
The last version of OpenFOAM to have sonicFoam in PISO form is 2.1.x: https://github.com/OpenFOAM/OpenFOAM...am/sonicFoam.C

As for the B graph, I guess you are referring to the residuals plot? If so, then it is possible that there was an implementation problem when merging the two solvers.

If you are referring to the B field itself, i.e. the results, it's possible that the results for the B field might actually make sense, depending on how the flow profile is going in the sonic range, because a very high pressure or high turbulence region can have significant impact on the electromagnetic profiles, since I can only imagine that the molecules do not take any specific orientation that would lead to a common magnetic orientation.

If using the sonicFoam from 2.1.x as a basis still gives you the same results/problems, then please follow the instructions given here: http://www.cfd-online.com/Forums/ope...-get-help.html

Best regards,
Bruno

M.N Hazwan Hadzir June 13, 2016 01:08

How to get the result after we run the MHD case in tutorial folder.
 
hello everyone,

i am new in OpenFoam user.
I have problems in producing result in MHD case. how i can take out the result data n graph from the simulation?
anybody can help me .


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