# MHD Shocktube test

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 November 20, 2015, 09:34 MHD Shocktube test #1 New Member   Ved Mukherjee Join Date: Nov 2015 Posts: 2 Rep Power: 0 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.

November 22, 2015, 08:11
#2
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Bruno Santos
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Quote:
 Originally Posted by vedlk Can anybody explain me the reason behind these problems.
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

Quote:
 Originally Posted by vedlk 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

 November 25, 2015, 03:14 #3 New Member   Ved Mukherjee Join Date: Nov 2015 Posts: 2 Rep Power: 0 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

 November 28, 2015, 13:24 #4 Retired Super Moderator   Bruno Santos Join Date: Mar 2009 Location: Lisbon, Portugal Posts: 10,975 Blog Entries: 45 Rep Power: 128 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 __________________ OpenFOAM: FAQ | Getting started Forum: How to get help, to post code/output and forum guide Read this before sending me PM

 June 13, 2016, 01:08 How to get the result after we run the MHD case in tutorial folder. #5 New Member   mohd nor hazwan bin hadzir Join Date: May 2016 Posts: 8 Rep Power: 10 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 .

 Tags graph result, mhd problem, result file