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<p><span style="font-family:"Calibri",sans-serif;color:black">Dear all:<o:p></o:p></span></p>
<p><span style="font-family:"Calibri",sans-serif;color:black">I am using FLASH to simulate the magnetohydrodynamics in laser generated plasmas. However, I always encounter a problem of negative internal energy both in FLASH 4.5 and FLASH4.6. Does anyone encounter
such a similar problem? The error information in the Log file is as follows: <o:p>
</o:p></span></p>
<p><strong><span style="font-family:DengXian;color:black"><o:p> </o:p></span></strong></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] [hy_uhd_ragelike] ERROR DETECTED<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] Zero or negative advected specific internal energy detected<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] DENS_OLD = 1.0000904290291E-09<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] DENS_NEW = 1.0000983091349E-09<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] UTOT_NEW = -3.7386802822434E-01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] UEXTRA = -1.7491864582091E+01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] UELE_NEW = -3.7135596091566E-01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] UION_NEW = -2.5120492887951E-03<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] URAD_NEW = -1.8019885718467E-08<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] EELE_VAR = 1.7001438966846E+10<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] EION_VAR = 1.1498940630502E+08<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] ERAD_VAR = 8.2498749422145E+02<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] EELE = -3.7131945682109E+08<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] EION = -2.5118023556785E+06<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] ERAD = -1.8018114373230E+01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] uele_adv = 1.7002978536045E+01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] uion_adv = 1.1501719275908E-01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] urad_adv = 8.2506210304961E-07<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PELE_VAR = 1.2145270532940E+00<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PION_VAR = 7.6660475248193E-02<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PRAD_VAR = 2.7502069901319E-07<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PELE_ADV = 1.2145343502140E+00<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PION_ADV = 7.6672066071296E-02<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] PRAD_ADV = 2.7502070101654E-07<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] TELE_VAR = 6.0996867323016E+02<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.488 ] TION_VAR = 3.6907447766733E+00<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] TRAD_VAR = 1.0219015193890E+02<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] CELL X = 3.3222656250000E-01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] CELL Y = 6.9890625000000E-01<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] CELL Z = 0.0000000000000E+00<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] You might be able to get things to keep running by trying<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 14:34:35.489 ] more diffusive hydro options (reduce CFL, order, etc...)<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 22:00:17.496 ] [hy_uhd_ragelike] Negative internal energies in 3T update<o:p></o:p></p>
<p class="MsoNormal">[ 04-16-2019 22:00:17.496 ] Falling back to using internal energy ratios instead of pressure ratios<o:p></o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
<p><span style="font-family:DengXian;color:black">I have tried many different RiemannSolvers. It does not help. I guess that this problem is related to the grid size, but I am not sure.</span><span style="font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p><span style="font-family:DengXian;color:black">Can anyone provide a solution to this problem? Thank you very much!</span><span style="font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p><span style="font-family:DengXian;color:black">Best regards,</span><span style="font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p><span style="font-family:DengXian;color:black">Wenyi Huo</span><span style="font-family:"Calibri",sans-serif;color:black"><o:p></o:p></span></p>
<p class="MsoNormal"><span style="font-family:"Calibri",sans-serif;color:black"><o:p> </o:p></span></p>
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