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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Christos,<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">It’s difficult to determine why this is happening without more information of what you’re trying to simulate. The ZPinch example problem uses several settings and units specific to Z-pinches, but it appears
that you are not simulating a Z-pinch. For example, it includes a current drive with B-field diffusing in from the upper-r boundary condition, and a ‘vacuum’ region with very high constant resistivity.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">I would need to know more about the modifications you made to the Simulation_* files, par file, Config, setup command, etc.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt;color:black">--</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Eddie Hansen</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Research Scientist</span><span style="color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Flash Center for Computational Science</span><span style="color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt"><o:p> </o:p></span></p>
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<p class="MsoNormal" style="margin-bottom:12.0pt"><b><span style="font-size:12.0pt;color:black">From:
</span></b><span style="font-size:12.0pt;color:black">flash-users <flash-users-bounces@flash.rochester.edu> on behalf of ddk172@edu.hmu.gr <ddk172@edu.hmu.gr><br>
<b>Date: </b>Friday, July 7, 2023 at 5:04 AM<br>
<b>To: </b>flash-users@flash.rochester.edu <flash-users@flash.rochester.edu><br>
<b>Subject: </b>[FLASH-USERS] MHD simulation of plasma focus machine<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hello everyone!<br>
I am trying to model a plasma focus machine using 2D flash, using a <br>
modified version of Z-Pinch example of FLASH4.7 version. Currently, i am <br>
running some simulations using Deuterium equation of state <br>
DD-006-imx.cn4 for plasma and vacuum. The density is very low (1.2e-6 <br>
gr/cm^3) and i assume is comparable to the vacuum density of MHD <br>
simulations. I have assumed a magnetic field deduced from the current i <br>
measured at the experiment, the initial conditions can be seen on <br>
attached figure. Early on the simulation( ~20ns) a problem arise that <br>
looks like numerical instability that is not familiar to me, as seen at <br>
the attached figure of density. This problem appears when magnetic <br>
resistivity flag is set true. Is anyone familiar with this kind of <br>
problem? If so, ask me for any additional information you need.<br>
<br>
Thanks in advance<br>
<br>
Christos Karvounis<o:p></o:p></span></p>
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