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<p class="MsoNormal"><span lang="DE">Dear all,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="DE"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">I’m running a modified version of the Z Pinch example, still using unsplit hydro etc, but without the electric current and hence with basically zero Magnetic field. For many initial conditions I’m running into trouble.
At the second timestep flash complains about temperature and pressure being NaN. I’ve traced the NaNs back to subroutine res_davieswen in the file<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">source/physics/materialProperties/MagneticResistivity/MagneticResistivityMain/DaviesWen/res_davieswen.F90<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">which is being called with only the <b>two mandatory arguments</b> solnVec and resPar by the unsplit hydro solver which resides in the file<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">source/physics/Hydro/HydroMain/unsplit/hy_uhd_unsplitUpdate.F90<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">With this combination the code for magnetic resistivity declares the variable tau and uses it to initialize the value of resPar, but itself is never initialized (it is only initialized if magnetic resistivity is called
with at least <b>three arguments</b>). Then, in many instances, tau is zero after declaration which results in resPar==0 which results in infinite magnetic resistivity. The infinity is then caught by the minimum located towards the end of the implementation
of magnetic resistivity and replaced by a very large number. However; this number is so large that an average over two magnetic resistivities of such a size yields infinity again which cause the NaNs in the rest of the code.
<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-US">So my question is: Is the if clause in the code for initializing tau:<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-US"><o:p> </o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-US">if (present(resPerp) .or. present(resCross)) then<o:p></o:p></span></b></p>
<p class="MsoNormal" style="text-indent:36.0pt">call PlasmaState_tau(ELE_ION, tele, llei, zbar, nion, tau)<span lang="EN-GB"><o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:36.0pt"><span lang="EN-GB">omega = res_dw_qele*xmag / (res_dw_mele*res_dw_speedlt)<o:p></o:p></span></p>
<p class="MsoNormal" style="text-indent:36.0pt"><span lang="EN-GB">…<o:p></o:p></span></p>
<p class="MsoNormal"><b><span lang="EN-GB">end if<o:p></o:p></span></b></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">really necessary or useful? If so, should there not be a different initialization of tau in case the body of this if clause is not executed?<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Best,<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB">Markus<o:p></o:p></span></p>
<p class="MsoNormal"><span lang="EN-GB"><o:p> </o:p></span></p>
<p style="margin-bottom:0cm"><span style="font-size:10.0pt;font-family:"Arial",sans-serif">- - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - - <br>
Dr. Markus Nöth<br>
Scientist<br>
+49 89 262023263<o:p></o:p></span></p>
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