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<p class="MsoNormal">Are you looking at total mass from the .dat file that is being outputted? For the default flash.par file for ZPinch, the file gets named ZPinch_2D.dat. Total mass should be the 2<sup>nd</sup> column.<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
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<p class="MsoNormal"><span style="color:black">--</span><span style="font-size:10.0pt;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="font-size:10.0pt;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Applications Group Leader<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="font-size:10.0pt;color:black"><o:p></o:p></span></p>
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<p class="MsoNormal"><o:p> </o:p></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">Alvaro Sanchez <alvaro.sanchez@greentownsbyfusion.com><br>
<b>Date: </b>Monday, October 30, 2023 at 10:21 AM<br>
<b>To: </b>Hansen, Eddie <ehansen@pas.rochester.edu>, flash-users@flash.rochester.edu <flash-users@flash.rochester.edu><br>
<b>Subject: </b>[EXT] Re: Question about total mass in ZPinch example<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Hello dear Eddie, firs of all thank you very much for your quick response, really appreciate it.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">I understand what you say about the vacuum but it is still too much of a raise (x10 as seen in picture) to be that the cause maybe?<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">If it is low density vacuum filling the domain left by the liner moving inward mass, then it should not raise that much, I think.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">We performed the same calculation for the Orszang-Tang test (we just modified the runtime, attached is total mass of the O-T test) and we still get weird results
for total mass. We also created a version of the Z-pinch where no vacuum is entering and we get similar results, with the mass increasing as compression happens.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">How can we check the species mass fractions? I am not finding them in the user's guide, probably this is all a mistake in our calculations, and we are doing something
wrong, but we have checked a lot of times and found no errors yet.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Thank you very much for your help, we are quite lost at the moment so everything is appreciated.<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"><o:p> </o:p></span></p>
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<p class="MsoNormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Alvaro
</span><span style="font-size:12.0pt;font-family:"Apple Color Emoji";color:black">🙂</span><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> <o:p></o:p></span></p>
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<p class="MsoNormal"><b><span style="color:black">From:</span></b><span style="color:black"> Hansen, Eddie <ehansen@pas.rochester.edu><br>
<b>Sent:</b> Friday, October 27, 2023 2:46 PM<br>
<b>To:</b> Alvaro Sanchez <alvaro.sanchez@greentownsbyfusion.com>; flash-users@flash.rochester.edu <flash-users@flash.rochester.edu><br>
<b>Subject:</b> Re: Question about total mass in ZPinch example</span> <o:p></o:p></p>
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<p class="MsoNormal"> <o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:11.0pt">Hello,</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt">The total mass of the ‘vacuum’ region should increase and that is by construction. As the liner and fuel move inwards, the vacuum region becomes larger. The BC along with a density floor effectively fills
in the increased vacuum region with more low-density vacuum material. We do this because otherwise there would be even lower densities in the vacuum that would result in very fast Alfven speeds, which would make the time steps too small to complete a simulation
in a reasonable amount of time.</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt">The important thing is for the vacuum ro remain at low enough densities to not impart any momentum onto the liner. The total masses of the fuel and liner should remain constant, and you can check this using
the species mass fractions.</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:11.0pt;color:black">--</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Eddie Hansen</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Applications Group Leader</span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Arial",sans-serif;color:#181A1B">Flash Center for Computational Science</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
<p class="xmsonormal"><span style="font-size:11.0pt"> </span><o:p></o:p></p>
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<p class="xmsonormal" 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 Alvaro Sanchez <alvaro.sanchez@greentownsbyfusion.com><br>
<b>Date: </b>Friday, October 27, 2023 at 5:52 AM<br>
<b>To: </b>flash-users@flash.rochester.edu <flash-users@flash.rochester.edu><br>
<b>Subject: </b>[FLASH-USERS] Question about total mass in ZPinch example</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Hello dear Flash users,</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">I have a concern about the ZPinch example, we have calculated total mass in a lot of variations of this example and we arrived at the conclusion that compression
increases the total mass within the domain.</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">In our experiments this happens when there are no outflow boundary, so the domain is closed. In the original ZPinch example this is not the case (since it has outlfow),
but still it can be observed the mass increasing by a factor of ten (show in attached picture)</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">We also calculated total mass in the Orszang-Tang example, and we also observed a weird increase in mass of 40%</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Do you know what's happening here?</span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black"> </span><o:p></o:p></p>
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<p class="xmsonormal"><span style="font-size:12.0pt;font-family:"Aptos",sans-serif;color:black">Thank you very much for your answer
</span><span style="font-size:12.0pt;font-family:"Apple Color Emoji";color:black">🙂</span><o:p></o:p></p>
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