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<p style="margin-top:0;margin-bottom:0">Hi Dante,</p>
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<p style="margin-top:0;margin-bottom:0">A few questions -</p>
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<p style="margin-top:0;margin-bottom:0">Do you have the pressure projection turned on? (p93-95)</p>
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<p style="margin-top:0;margin-bottom:0">What is your iteration tolerance (p22, divergence) ?</p>
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<p style="margin-top:0;margin-bottom:0">Paul</p>
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<div id="divRplyFwdMsg" dir="ltr"><font face="Calibri, sans-serif" style="font-size:11pt" color="#000000"><b>From:</b> Nek5000-users <nek5000-users-bounces@lists.mcs.anl.gov> on behalf of nek5000-users@lists.mcs.anl.gov <nek5000-users@lists.mcs.anl.gov><br>
<b>Sent:</b> Wednesday, May 16, 2018 3:34:42 AM<br>
<b>To:</b> nek5000-users@lists.mcs.anl.gov<br>
<b>Subject:</b> [Nek5000-users] gmers solver issue</font>
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<p class="x_MsoNormal">Hello,</p>
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<p class="x_MsoNormal">I trying to run the DNS of a pipe-like configuration with NEK-5000 but I’m facing some issues that I cannot fully understand.</p>
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<p class="x_MsoNormal">More specifically, I am using the PN-PN formulation and the simulation slows down drastically after certain time. I have observed that when</p>
<p class="x_MsoNormal">this happens the number of GMRES iteration for the pressure solver increases (from 50 at the beginning of the simulation to 170)</p>
<p class="x_MsoNormal">and the norm of the divergence of the velocity increases and I get a WARNING DIV(V)-QTL to large (~ 1.2E-1).</p>
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<p class="x_MsoNormal">The problem appeared initially using a 3rd order polynomial, but even using higher order (9<sup>
</sup>th) does not solve the issue.</p>
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<p class="x_MsoNormal">Do you have some hints about the nature of this issue?</p>
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<p class="x_MsoNormal"><span style="">Kind regards,<b></b></span></p>
<p class="x_MsoNormal"><span style="">Dante </span></p>
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