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Thanks Paul!<div>I am also thinking of having a precursor simulation of flow inside nozzle and therefore, replacing it with a prescribed inflow BC. </div><div><br></div><div>Mohsen</div><div><br><div><div>On 21-Apr-14, at 8:00 PM, <<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>> wrote:</div><br class="Apple-interchange-newline"><blockquote type="cite"> <div style="direction: ltr;font-family: Tahoma;color: #000000;font-size: 10pt;"> <div><br> </div> Dear Mohsen, <div><br> </div> <div>Years ago we did support internal walls, but that's no longer the case with the current workflow.</div> <div><br> </div> <div>The issue is that the gridpoints across the interface are identified as being one and the same if</div> <div>they are physically adjacent. It would be possible to hack into your vertex numbering to make</div> <div>these different (i.e., after they are generated by genmap), or to make a geometry in which they</div> <div>are distinct by having a finite-thickness wall, but either way requires some application specific</div> <div>coding in your usr file or modifications to your map file.</div> <div><br> </div> <div>Paul</div> <div><br> <div style="font-family: Times New Roman; color: #000000; font-size: 16px"> <hr tabindex="-1"> <div id="divRpF512439" style="direction: ltr;"><font face="Tahoma" size="2" color="#000000"><b>From:</b> <a href="mailto:nek5000-users-bounces@lists.mcs.anl.gov">nek5000-users-bounces@lists.mcs.anl.gov</a> [<a href="mailto:nek5000-users-bounces@lists.mcs.anl.gov">nek5000-users-bounces@lists.mcs.anl.gov</a>] on behalf of <a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a> [<a href="mailto:nek5000-users@lists.mcs.anl.gov">nek5000-users@lists.mcs.anl.gov</a>]<br> <b>Sent:</b> Monday, April 21, 2014 6:12 PM<br> <b>To:</b> Nek 5000<br> <b>Subject:</b> [Nek5000-users] Internal boundary condition<br> </font><br> </div> <div></div> <div>Dear all, <div>I have a question regarding the internal boundary condition in the code. </div> <div>My problem consists of a fan-shaped nozzle, which parts of its walls are located within the flow domain (a cylindrical tank with inflow/outflow boundary conditions). The question is how to set the boundary conditions for such internal zero-thickness walls?</div> <div><br> </div> <div>I thought the walls could be defined as internal faces by creating a side-set (in the Cubit) and setting the velocity and the temperature fields of these faces to 'W ' and 'E ', respectively, similar to the solid-fluid interface in the conjugate heat transfer example. Nevertheless, there is a fluid at both sides of the interface in this case.</div> <div>Below is part of the boundary conditions in .rea file.</div> <div>.....</div> <div>.....</div> <div> <div>1 0 <span class="Apple-tab-span" style="white-space:pre"></span>! 1 fluid set, 0 other/solid sets</div> <div>10<span class="Apple-tab-span" style="white-space:pre"> </span> <span class="Apple-tab-span" style="white-space:pre"> </span>! fluid set is 10</div> <div>1<span class="Apple-tab-span" style="white-space:pre"> </span><span class="Apple-tab-span" style="white-space:pre"></span>! block 10 is material 1</div> <div>10 <span class="Apple-tab-span" style="white-space:pre"> </span>! no. bc sets (side-sets); bc set id,</div> <div>100 1 W , <span class="Apple-tab-span" style="white-space:pre"></span>(external walls)</div> <div>100 2 I ,<span class="Apple-tab-span" style="white-space:pre"> </span>(external walls)</div> <div>120 1 W ,<span class="Apple-tab-span" style="white-space:pre"> </span>(internal walls corresponding to the nozzle)</div> <div><font class="Apple-style-span" face="Symbol">120 2 E ,</font><span class="Apple-tab-span" style="white-space:pre"><font class="Apple-style-span" face="Symbol"> </font></span>(internal walls corresponding to the nozzle)</div> <div><span class="Apple-tab-span" style="white-space:pre"></span></div> <div>200 1 v ,<span class="Apple-tab-span" style="white-space:pre"> </span>(inflow)</div> <div>200 2 t ,<span class="Apple-tab-span" style="white-space:pre"> </span>(inflow)</div> <div>300 1 O ,<span class="Apple-tab-span" style="white-space:pre"> </span>(outflow)</div> <div>300 2 O ,<span class="Apple-tab-span" style="white-space:pre"> </span>(outflow)</div> <div>400 1 SYM,</div> <div>400 2 SYM,</div> </div> <div>.....</div> <div>.....</div> <div><br> </div> <div> <div>When I run this case, warning messages appear during assigning the sidesets to the element faces, saying that: "face shared by 2 Hexes (say) 2331 5227". It seems that this warning is only because I defined some faces as "internal", however, no "other solid/fluids" has been defined in the input file.</div> <div>Nevertheless, the issue with such definition is that, although, the velocity field is zero at the internal walls, there seems to be a pressure gradient across the wall, which is not physically consistent with internal walls, and drives a flow through the walls.</div> </div> <div><br> </div> <div>It would be appreciated if anyone could help me on this problem.</div> <div><br> </div> <div>Thanks,</div> <div>Mohsen</div> <div><br> </div> </div> </div> </div> </div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">_______________________________________________</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; ">Nek5000-users mailing list</div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="mailto:Nek5000-users@lists.mcs.anl.gov">Nek5000-users@lists.mcs.anl.gov</a></div><div style="margin-top: 0px; margin-right: 0px; margin-bottom: 0px; margin-left: 0px; "><a href="https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users">https://lists.mcs.anl.gov/mailman/listinfo/nek5000-users</a></div> </blockquote></div><br></div></body></html>