<div dir="ltr"><div>Thank you very much!</div><div dir="ltr"></div><br><br><div class="gmail_quote"><blockquote class="gmail_quote" style="margin:0px 0px 0px 0.8ex;border-left:1px solid rgb(204,204,204);padding-left:1ex"><br>Send Users mailing list submissions to<br>
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1. Re: (no subject) (Zach Etienne)<br>
2. Re: (no subject) (Zach Etienne)<br>
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----------------------------------------------------------------------<br>
<br>
Message: 1<br>
Date: Wed, 12 Feb 2020 23:14:50 -0500<br>
From: Zach Etienne <<a href="mailto:zachetie@gmail.com" target="_blank">zachetie@gmail.com</a>><br>
Subject: Re: [Users] (no subject)<br>
To: ZhiChao Zhao <<a href="mailto:yanyuechuixue@gmail.com" target="_blank">yanyuechuixue@gmail.com</a>><br>
Cc: Einstein Toolkit Users <<a href="mailto:users@einsteintoolkit.org" target="_blank">users@einsteintoolkit.org</a>><br>
Message-ID:<br>
<<a href="mailto:CAP6hNvzOc_XR-M33McaNH6bMBu76uc1yrXZaX0B6E5NpzZmQJw@mail.gmail.com" target="_blank">CAP6hNvzOc_XR-M33McaNH6bMBu76uc1yrXZaX0B6E5NpzZmQJw@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
One quick clarification:<br>
<br>
When I said<br>
> "[integrated measures of rest mass over a volume] can become completely<br>
unreliable at the time of black hole formation"<br>
<br>
I meant that the conservative nature of GRMHD schemes can and do break down<br>
inside black holes, so mass might be lost after it passes inside a black<br>
hole horizon. This should have no ill effect outside the horizon, as "what<br>
happens in the horizon stays in the horizon". Generally you'd want to<br>
perform a surface integral to monitor the rest mass passing into the<br>
horizon and combine it with a volume integral outside the horizon to<br>
measure the total rest mass after black hole formation.<br>
<br>
-Zach<br>
<br>
* * *<br>
Prof. Zachariah Etienne<br>
Physics & Astronomy Dept.<br>
West Virginia University<br>
<a href="http://astro.phys.wvu.edu/zetienne/" rel="noreferrer" target="_blank">http://astro.phys.wvu.edu/zetienne/</a><br>
<a href="http://blackholesathome.net" rel="noreferrer" target="_blank">http://blackholesathome.net</a><br>
<<a href="https://blackholesathome.net" rel="noreferrer" target="_blank">https://blackholesathome.net</a>><br>
<br>
<br>
On Wed, Feb 12, 2020 at 11:05 PM Zach Etienne <<a href="mailto:zachetie@gmail.com" target="_blank">zachetie@gmail.com</a>> wrote:<br>
<br>
> Hi ZhiChao,<br>
><br>
> > The program runs without error, however there is no eject during the<br>
> merge.<br>
><br>
> Typical ejecta from BNS mergers amount to a very tiny fraction of the<br>
> total initial mass, with values of 1e-3 Msun from BNS merger simulations<br>
> being reported in the literature (<a href="https://arxiv.org/abs/1809.11161" rel="noreferrer" target="_blank">https://arxiv.org/abs/1809.11161</a>). This<br>
> value is highly dependent on the equation of state however. Further most<br>
> simulations reporting ejecta are not performed at multiple numerical<br>
> resolutions, meaning that the values may be adjusted downwards with<br>
> subsequent simulations. Indeed in most simulations I saw for which more<br>
> than one resolution was performed in that paper, the higher resolution<br>
> simulation has less ejecta (see Table 2)--sometimes significantly less<br>
> (e.g., LS220_M140140_LK).<br>
><br>
> Bottom line, I am not surprised you didn't see any ejecta. Ejecta<br>
> measurements are often dominated by numerical error, and depend sensitively<br>
> on equation of state. The very simple equation of state you chose (simple<br>
> Gamma=2 polytrope) might not exhibit much, if any, ejecta in the limit of<br>
> very high resolution.<br>
><br>
> A recent update to IllinoisGRMHD supports more sophisticated (piecewise<br>
> polytrope/"hybrid") equations of state. It exists within the IllinoisGRMHD<br>
> subdirectory of <a href="https://github.com/zachetienne/nrpytutorial" rel="noreferrer" target="_blank">https://github.com/zachetienne/nrpytutorial</a> . You might<br>
> have more luck getting ejecta from BNS initial data with<br>
> piecewise-polytrope equations of state.<br>
><br>
> > And "restmass. Init. IN sphere @<br>
> (0.000000e+00,0.000000e+00,0.000000e+00), r=2.708902e+02. Moves/Tracks AMR<br>
> Centre -1/-1" is increasing.<br>
><br>
> If I'm interpreting this correctly (I might not be), you are measuring<br>
> total rest mass within 270.89 in code units. You seem to observe an<br>
> increase of 0.06% over the course of the simulation. That's not much, and<br>
> can happen due to interpolation errors at AMR refinement boundaries (matter<br>
> crosses AMR refinement boundaries and tiny errors add up to a small boost<br>
> in mass), or become completely unreliable at the time of black hole<br>
> formation. Performing another simulation at higher or lower resolution and<br>
> additional volume integral regions may help diagnose this measurement. I<br>
> think you'd want to analyze the rest mass *outside* an interior volume to<br>
> estimate ejecta anyway.<br>
><br>
> A more sophisticated interpolation treatment at AMR refinement boundaries<br>
> might help reduce this error, which amounts to a different prolongation<br>
> type (e.g., ENO) being chosen for evolved GRMHD variables.<br>
><br>
> Hope this helps.<br>
><br>
> -Zach<br>
><br>
> * * *<br>
> Prof. Zachariah Etienne<br>
> Physics & Astronomy Dept.<br>
> West Virginia University<br>
> <a href="http://astro.phys.wvu.edu/zetienne/" rel="noreferrer" target="_blank">http://astro.phys.wvu.edu/zetienne/</a><br>
> <a href="http://blackholesathome.net" rel="noreferrer" target="_blank">http://blackholesathome.net</a><br>
> <<a href="https://blackholesathome.net" rel="noreferrer" target="_blank">https://blackholesathome.net</a>><br>
><br>
><br>
> On Wed, Feb 12, 2020 at 9:25 PM ZhiChao Zhao <<a href="mailto:yanyuechuixue@gmail.com" target="_blank">yanyuechuixue@gmail.com</a>><br>
> wrote:<br>
><br>
>> Hello everyone,<br>
>><br>
>> I am Zhi-Chao Zhao from Beijing Normal University, China.<br>
>> I am using EinsteinToolkit and IllinoisGRMHD to simulate BNS merge.<br>
>><br>
>> I use a par file modified from<br>
>> <a href="https://bitbucket.org/zach_etienne/wvuthorns_diagnostics/src/master/NSNS_parameter_files/nsns_test.par" rel="noreferrer" target="_blank">https://bitbucket.org/zach_etienne/wvuthorns_diagnostics/src/master/NSNS_parameter_files/nsns_test.par</a><br>
>> .<br>
>> I just add one line<br>
>> "VolumeIntegrals_GRMHD::volintegral_inside_sphere__radius[6] =<br>
>> 270.89015422746235".<br>
>><br>
>> The initial data is got from Zach Etienne.<br>
>><br>
>> The program runs without error, however there is no eject during the<br>
>> merge.<br>
>> Two videos:<br>
>> <a href="https://gogo.treenew.be/rho_b_movie.mpg" rel="noreferrer" target="_blank">https://gogo.treenew.be/rho_b_movie.mpg</a><br>
>> <a href="https://gogo.treenew.be/rho_b_log_movie.mpg" rel="noreferrer" target="_blank">https://gogo.treenew.be/rho_b_log_movie.mpg</a><br>
>><br>
>><br>
>> And "restmass. Init. IN sphere @<br>
>> (0.000000e+00,0.000000e+00,0.000000e+00), r=2.708902e+02. Moves/Tracks AMR<br>
>> Centre -1/-1" is increasing.<br>
>> One figure:<br>
>> <a href="https://gogo.treenew.be/newplot.png" rel="noreferrer" target="_blank">https://gogo.treenew.be/newplot.png</a><br>
>><br>
>> I don't know where I went wrong. Can anyone help me?<br>
>><br>
>><br>
>> _______________________________________________<br>
>> Users mailing list<br>
>> <a href="mailto:Users@einsteintoolkit.org" target="_blank">Users@einsteintoolkit.org</a><br>
>> <a href="http://lists.einsteintoolkit.org/mailman/listinfo/users" rel="noreferrer" target="_blank">http://lists.einsteintoolkit.org/mailman/listinfo/users</a><br>
>><br>
><br>
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<br>
Message: 2<br>
Date: Thu, 13 Feb 2020 00:00:17 -0500<br>
From: Zach Etienne <<a href="mailto:zachetie@gmail.com" target="_blank">zachetie@gmail.com</a>><br>
Subject: Re: [Users] (no subject)<br>
To: ZhiChao Zhao <<a href="mailto:yanyuechuixue@gmail.com" target="_blank">yanyuechuixue@gmail.com</a>><br>
Cc: Einstein Toolkit Users <<a href="mailto:users@einsteintoolkit.org" target="_blank">users@einsteintoolkit.org</a>><br>
Message-ID:<br>
<CAP6hNvw=<a href="mailto:87t3vEDbRw0-q93zEuJsQn2_vZQXJCzYc_dv7S7TKg@mail.gmail.com" target="_blank">87t3vEDbRw0-q93zEuJsQn2_vZQXJCzYc_dv7S7TKg@mail.gmail.com</a>><br>
Content-Type: text/plain; charset="utf-8"<br>
<br>
Hi ZhiChao,<br>
<br>
One more note: The BNS simulation you performed was an equal-mass case.<br>
You should find that the amount of ejecta will be much larger if you chose<br>
a significantly unequal-mass system. You will want to adjust the AMR grid<br>
structure accordingly before proceeding on this front.<br>
<br>
-Zach<br>
<br>
* * *<br>
Prof. Zachariah Etienne<br>
Physics & Astronomy Dept.<br>
West Virginia University<br>
<a href="http://astro.phys.wvu.edu/zetienne/" rel="noreferrer" target="_blank">http://astro.phys.wvu.edu/zetienne/</a><br>
<a href="http://blackholesathome.net" rel="noreferrer" target="_blank">http://blackholesathome.net</a><br>
<<a href="https://blackholesathome.net" rel="noreferrer" target="_blank">https://blackholesathome.net</a>><br>
<br>
<br>
On Wed, Feb 12, 2020 at 11:14 PM Zach Etienne <<a href="mailto:zachetie@gmail.com" target="_blank">zachetie@gmail.com</a>> wrote:<br>
<br>
> One quick clarification:<br>
><br>
> When I said<br>
> > "[integrated measures of rest mass over a volume] can become completely<br>
> unreliable at the time of black hole formation"<br>
><br>
> I meant that the conservative nature of GRMHD schemes can and do break<br>
> down inside black holes, so mass might be lost after it passes inside a<br>
> black hole horizon. This should have no ill effect outside the horizon, as<br>
> "what happens in the horizon stays in the horizon". Generally you'd want to<br>
> perform a surface integral to monitor the rest mass passing into the<br>
> horizon and combine it with a volume integral outside the horizon to<br>
> measure the total rest mass after black hole formation.<br>
><br>
> -Zach<br>
><br>
> * * *<br>
> Prof. Zachariah Etienne<br>
> Physics & Astronomy Dept.<br>
> West Virginia University<br>
> <a href="http://astro.phys.wvu.edu/zetienne/" rel="noreferrer" target="_blank">http://astro.phys.wvu.edu/zetienne/</a><br>
> <a href="http://blackholesathome.net" rel="noreferrer" target="_blank">http://blackholesathome.net</a><br>
> <<a href="https://blackholesathome.net" rel="noreferrer" target="_blank">https://blackholesathome.net</a>><br>
><br>
><br>
> On Wed, Feb 12, 2020 at 11:05 PM Zach Etienne <<a href="mailto:zachetie@gmail.com" target="_blank">zachetie@gmail.com</a>> wrote:<br>
><br>
>> Hi ZhiChao,<br>
>><br>
>> > The program runs without error, however there is no eject during the<br>
>> merge.<br>
>><br>
>> Typical ejecta from BNS mergers amount to a very tiny fraction of the<br>
>> total initial mass, with values of 1e-3 Msun from BNS merger simulations<br>
>> being reported in the literature (<a href="https://arxiv.org/abs/1809.11161" rel="noreferrer" target="_blank">https://arxiv.org/abs/1809.11161</a>).<br>
>> This value is highly dependent on the equation of state however. Further<br>
>> most simulations reporting ejecta are not performed at multiple numerical<br>
>> resolutions, meaning that the values may be adjusted downwards with<br>
>> subsequent simulations. Indeed in most simulations I saw for which more<br>
>> than one resolution was performed in that paper, the higher resolution<br>
>> simulation has less ejecta (see Table 2)--sometimes significantly less<br>
>> (e.g., LS220_M140140_LK).<br>
>><br>
>> Bottom line, I am not surprised you didn't see any ejecta. Ejecta<br>
>> measurements are often dominated by numerical error, and depend sensitively<br>
>> on equation of state. The very simple equation of state you chose (simple<br>
>> Gamma=2 polytrope) might not exhibit much, if any, ejecta in the limit of<br>
>> very high resolution.<br>
>><br>
>> A recent update to IllinoisGRMHD supports more sophisticated (piecewise<br>
>> polytrope/"hybrid") equations of state. It exists within the IllinoisGRMHD<br>
>> subdirectory of <a href="https://github.com/zachetienne/nrpytutorial" rel="noreferrer" target="_blank">https://github.com/zachetienne/nrpytutorial</a> . You might<br>
>> have more luck getting ejecta from BNS initial data with<br>
>> piecewise-polytrope equations of state.<br>
>><br>
>> > And "restmass. Init. IN sphere @<br>
>> (0.000000e+00,0.000000e+00,0.000000e+00), r=2.708902e+02. Moves/Tracks AMR<br>
>> Centre -1/-1" is increasing.<br>
>><br>
>> If I'm interpreting this correctly (I might not be), you are measuring<br>
>> total rest mass within 270.89 in code units. You seem to observe an<br>
>> increase of 0.06% over the course of the simulation. That's not much, and<br>
>> can happen due to interpolation errors at AMR refinement boundaries (matter<br>
>> crosses AMR refinement boundaries and tiny errors add up to a small boost<br>
>> in mass), or become completely unreliable at the time of black hole<br>
>> formation. Performing another simulation at higher or lower resolution and<br>
>> additional volume integral regions may help diagnose this measurement. I<br>
>> think you'd want to analyze the rest mass *outside* an interior volume to<br>
>> estimate ejecta anyway.<br>
>><br>
>> A more sophisticated interpolation treatment at AMR refinement boundaries<br>
>> might help reduce this error, which amounts to a different prolongation<br>
>> type (e.g., ENO) being chosen for evolved GRMHD variables.<br>
>><br>
>> Hope this helps.<br>
>><br>
>> -Zach<br>
>><br>
>> * * *<br>
>> Prof. Zachariah Etienne<br>
>> Physics & Astronomy Dept.<br>
>> West Virginia University<br>
>> <a href="http://astro.phys.wvu.edu/zetienne/" rel="noreferrer" target="_blank">http://astro.phys.wvu.edu/zetienne/</a><br>
>> <a href="http://blackholesathome.net" rel="noreferrer" target="_blank">http://blackholesathome.net</a><br>
>> <<a href="https://blackholesathome.net" rel="noreferrer" target="_blank">https://blackholesathome.net</a>><br>
>><br>
>><br>
>> On Wed, Feb 12, 2020 at 9:25 PM ZhiChao Zhao <<a href="mailto:yanyuechuixue@gmail.com" target="_blank">yanyuechuixue@gmail.com</a>><br>
>> wrote:<br>
>><br>
>>> Hello everyone,<br>
>>><br>
>>> I am Zhi-Chao Zhao from Beijing Normal University, China.<br>
>>> I am using EinsteinToolkit and IllinoisGRMHD to simulate BNS merge.<br>
>>><br>
>>> I use a par file modified from<br>
>>> <a href="https://bitbucket.org/zach_etienne/wvuthorns_diagnostics/src/master/NSNS_parameter_files/nsns_test.par" rel="noreferrer" target="_blank">https://bitbucket.org/zach_etienne/wvuthorns_diagnostics/src/master/NSNS_parameter_files/nsns_test.par</a><br>
>>> .<br>
>>> I just add one line<br>
>>> "VolumeIntegrals_GRMHD::volintegral_inside_sphere__radius[6] =<br>
>>> 270.89015422746235".<br>
>>><br>
>>> The initial data is got from Zach Etienne.<br>
>>><br>
>>> The program runs without error, however there is no eject during the<br>
>>> merge.<br>
>>> Two videos:<br>
>>> <a href="https://gogo.treenew.be/rho_b_movie.mpg" rel="noreferrer" target="_blank">https://gogo.treenew.be/rho_b_movie.mpg</a><br>
>>> <a href="https://gogo.treenew.be/rho_b_log_movie.mpg" rel="noreferrer" target="_blank">https://gogo.treenew.be/rho_b_log_movie.mpg</a><br>
>>><br>
>>><br>
>>> And "restmass. Init. IN sphere @<br>
>>> (0.000000e+00,0.000000e+00,0.000000e+00), r=2.708902e+02. Moves/Tracks AMR<br>
>>> Centre -1/-1" is increasing.<br>
>>> One figure:<br>
>>> <a href="https://gogo.treenew.be/newplot.png" rel="noreferrer" target="_blank">https://gogo.treenew.be/newplot.png</a><br>
>>><br>
>>> I don't know where I went wrong. Can anyone help me?<br>
>>><br>
>>><br>
>>> _______________________________________________<br>
>>> Users mailing list<br>
>>> <a href="mailto:Users@einsteintoolkit.org" target="_blank">Users@einsteintoolkit.org</a><br>
>>> <a href="http://lists.einsteintoolkit.org/mailman/listinfo/users" rel="noreferrer" target="_blank">http://lists.einsteintoolkit.org/mailman/listinfo/users</a><br>
>>><br>
>><br>
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End of Users Digest, Vol 119, Issue 10<br>
**************************************<br>
</blockquote></div><br clear="all"><div><br></div>-- <br><div dir="ltr" class="gmail_signature"><div dir="ltr"><div>赵志超</div><div>中国科学院高能物理研究所</div><div>中国 北京</div><div>18401696963</div><div><a href="mailto:yanyuechuixue@gmail.com" target="_blank">yanyuechuixue@gmail.com</a></div></div></div></div>