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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Zhao,<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 suspect these resistivity values (1.e-20 and 1.e-18) are too low to observe a significant difference in the simulation…<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 see in your par file that you specified ‘CGS’ units, so this means that ‘resistivity’ will be multiplied by a factor of c^2/(4*pi) to get magnetic diffusivity eta in terms of cm^2/s.<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">eta = resistivity*c^2/(4*pi)<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">Now, as a rough estimate, the magnetic field will diffuse a distance L in a time t according to:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">L = sqrt(t*eta)<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">Your simulation is 4 ns long, so putting this all together:<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resistivity = 1.e-20 </span><span style="font-size:11.0pt;font-family:Wingdings"></span><span style="font-size:11.0pt"> L ~ 0.5 um<o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-size:11.0pt">resistivity = 1.e-18 </span><span style="font-size:11.0pt;font-family:Wingdings"></span><span style="font-size:11.0pt"> L ~ 5 um<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">Both numbers are smaller than your resolution which has a minimum value of 15.625 um in the z-direction (it’s not absolutely necessary, but I would recommend making resolution the same in each direction if
possible). So a couple of things to try:<o:p></o:p></span></p>
<ol style="margin-top:0in" start="1" type="1">
<li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">increase resistivity<o:p></o:p></span></li><li class="MsoListParagraph" style="margin-left:0in;mso-list:l0 level1 lfo1"><span style="font-size:11.0pt">decrease cell width<o:p></o:p></span></li></ol>
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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 Ryan Farber <rjfarber@umich.edu><br>
<b>Date: </b>Thursday, May 4, 2023 at 2:03 PM<br>
<b>To: </b>Reyes, Adam <adam.reyes@rochester.edu><br>
<b>Cc: </b>flash-users <flash-users@flash.rochester.edu><br>
<b>Subject: </b>Re: [FLASH-USERS] [EXT] Re: resistivity problems<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">I'm not sure what the typical units / scaling FLASH does for magnetic resistivity, but 1e-18 and below sounds like it's smaller than double point floating precision. At least as another debugging test you
might try a value of unity.<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>
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<p class="MsoNormal"><span style="font-size:11.0pt">Best,<br clear="all">
<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>
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<p class="MsoNormal"><span style="font-size:11.0pt">Ryan<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>
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<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">On Thu, May 4, 2023 at 7:16 PM Adam Reyes <<a href="mailto:adam.reyes@rochester.edu">adam.reyes@rochester.edu</a>> wrote:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Hi Zhao,<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>
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<p class="MsoNormal"><span style="font-size:11.0pt">I don't see any issues with how you're setting the resistivity. Are your simulations producing the magnetic fields that you expect? I'm surprised you don't see any differences between the runs at different
resistivities. <br clear="all">
<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">*************************************************************************<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">Adam Reyes<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black"><img border="0" id="_x0000_i1026" src="https://flash.rochester.edu/site/common/images/email_signature/FLASH.jpg"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">Code Group Leader, Flash Center for Computational Science <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">Research Scientist, Dept. of Physics and Astronomy<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">University of Rochester<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">River Campus: Bausch and Lomb Hall, 369 <o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">500 Wilson Blvd. PO Box 270171, Rochester, NY 14627<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">Email <a href="mailto:adam.reyes@rochester.edu" target="_blank">adam.reyes@rochester.edu</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black">Web <a href="https://flash.rochester.edu/" target="_blank">https://flash.rochester.edu</a><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black"> (he / him / his)<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;color:black"><img border="0" id="_x0000_i1025" src="https://flash.rochester.edu/site/common/images/email_signature/FLASH-pride-sml.png"><o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:9.0pt;font-family:Helvetica;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>
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<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">On Thu, May 4, 2023 at 10:34 AM
</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">赵</span><span style="font-size:11.0pt;font-family:"MS Gothic"">旭</span><span style="font-size:11.0pt"> <<a href="mailto:xuzhao1994@sjtu.edu.cn" target="_blank">xuzhao1994@sjtu.edu.cn</a>>
wrote:<o:p></o:p></span></p>
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<p class="MsoNormal"><span style="font-size:11.0pt">Dear Adam,<br>
<br>
Thank you very much for your reply.<br>
<br>
This simulation is try to use FLASH to simulate the magnetic reconnection in a 'coil' target configuration.<br>
<br>
I tried to set the resistivity from 0, 1e-20, and 1e-18 (for testing), respectively.<br>
<br>
I want to see the transition from magnetic energy to kinetic energy when the reconnection occurs.<br>
<br>
However, it seems nothing changes in these simultions (Both plasma evolution and the value of magnetic energy/kinetic energy).<br>
<br>
The log and .par file are attached.<br>
<br>
Any suggestion helps as I have struggled for a while for this problem.<br>
<br>
Best,<br>
Zhao<br>
<br>
----- </span><span style="font-size:11.0pt;font-family:"MS Gothic"">原始</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">邮</span><span style="font-size:11.0pt;font-family:"MS Gothic"">件</span><span style="font-size:11.0pt"> -----<br>
</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">发</span><span style="font-size:11.0pt;font-family:"MS Gothic"">件人</span><span style="font-size:11.0pt">: "Adam Reyes" <<a href="mailto:adam.reyes@rochester.edu" target="_blank">adam.reyes@rochester.edu</a>><br>
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">收件人</span><span style="font-size:11.0pt">: "</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">赵</span><span style="font-size:11.0pt;font-family:"MS Gothic"">旭</span><span style="font-size:11.0pt">"
<<a href="mailto:xuzhao1994@sjtu.edu.cn" target="_blank">xuzhao1994@sjtu.edu.cn</a>><br>
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">抄送</span><span style="font-size:11.0pt">: "flash-users" <<a href="mailto:flash-users@flash.rochester.edu" target="_blank">flash-users@flash.rochester.edu</a>><br>
</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">发</span><span style="font-size:11.0pt;font-family:"MS Gothic"">送</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">时间</span><span style="font-size:11.0pt">:
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">星期四</span><span style="font-size:11.0pt">, 2023</span><span style="font-size:11.0pt;font-family:"MS Gothic"">年</span><span style="font-size:11.0pt"> 5
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">月</span><span style="font-size:11.0pt"> 04</span><span style="font-size:11.0pt;font-family:"MS Gothic"">日</span><span style="font-size:11.0pt">
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">下午</span><span style="font-size:11.0pt"> 9:51:44<br>
</span><span style="font-size:11.0pt;font-family:"MS Gothic"">主</span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">题</span><span style="font-size:11.0pt">: Re: [FLASH-USERS] resistivity problems<br>
<br>
Hi Zhao,<br>
<br>
Do you have a logfile from the FLASH simulation that you could share? These<br>
contain details of how the code was configured for your simulation so we<br>
can give a more specific suggestion.<br>
<br>
*************************************************************************<br>
Adam Reyes<br>
<br>
Code Group Leader, Flash Center for Computational Science<br>
Research Scientist, Dept. of Physics and Astronomy<br>
University of Rochester<br>
River Campus: Bausch and Lomb Hall, 369<br>
500 Wilson Blvd. PO Box 270171, Rochester, NY 14627<br>
Email <a href="mailto:adam.reyes@rochester.edu" target="_blank">adam.reyes@rochester.edu</a><br>
Web <a href="https://flash.rochester.edu" target="_blank">https://flash.rochester.edu</a><br>
(he / him / his)<br>
<br>
*************************************************************************<br>
<br>
On Thu, May 4, 2023 at 9:43 AM </span><span style="font-size:11.0pt;font-family:"PingFang TC",sans-serif">赵</span><span style="font-size:11.0pt;font-family:"MS Gothic"">旭</span><span style="font-size:11.0pt"> <<a href="mailto:xuzhao1994@sjtu.edu.cn" target="_blank">xuzhao1994@sjtu.edu.cn</a>>
wrote:<br>
<br>
> Dear FLASH users/developers,<br>
><br>
><br>
> When I want to set up a non-ideal plasma magnetic resistivity condition in<br>
> 3D laser-driven experiment simulation, a mistake trouble me.<br>
><br>
> I change the resistivity of plasma at constant condition, but the<br>
> simulation results didn't change. I use the CGS system. Do I made any<br>
> mistakes in in FLASH?<br>
><br>
> Any suggestion helps.<br>
><br>
><br>
> Zhao<br>
><br>
> --<br>
> Zhao Xu<br>
> Laboratory for Laser Plasmas (MoE)<br>
> Shanghai Jiao Tong University<br>
> 800 Dongchuan Rd, Shanghai 200240<br>
> _______________________________________________<br>
> flash-users mailing list<br>
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><br>
> For list info, including unsubscribe:<br>
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https://flash.rochester.edu/mailman/listinfo/flash-users</a><br>
><br>
-- <br>
Zhao Xu<br>
Laboratory for Laser Plasmas (MoE)<br>
Shanghai Jiao Tong University<br>
800 Dongchuan Rd, Shanghai 200240<o:p></o:p></span></p>
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