<html><body><div style="color:#000; background-color:#fff; font-family:HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif;font-size:16px"><div><span></span></div><div id="yui_3_16_0_1_1424339378984_5935" dir="ltr">Hi Christophe, Gmshers,</div><div id="yui_3_16_0_1_1424339378984_5938" dir="ltr">I found a work around for my simple geometry with shared internal faces which might work for others</div><div id="yui_3_16_0_1_1424339378984_5991" dir="ltr">It concerns cases where STEP (or other OCC probably) geometry won't import correctly into gmsh </div><div id="yui_3_16_0_1_1424339378984_6380" dir="ltr">with the cut and merge faces option enabled i.e. bits disappear or still have duplicate elementary entities.<br></div><div id="yui_3_16_0_1_1424339378984_6381" dir="ltr"><br></div><div id="yui_3_16_0_1_1424339378984_6389" dir="ltr">Work arounds so far.</div><div id="yui_3_16_0_1_1424339378984_6058" dir="ltr"><br>1) Import STEP file into GiD 11.1.9d (free Evaluation version but may not work with large models?) </div><div id="yui_3_16_0_1_1424339378984_6057" dir="ltr">then do geometry>edit>collapse>model then utilities>repair model. Then export as iges.</div><div id="yui_3_16_0_1_1424339378984_6107" dir="ltr"><br>Use this iges file in merge"file.igs"; in a .geo file (disable the cut and merge faces option) </div><div id="yui_3_16_0_1_1424339378984_6125" dir="ltr">if you want you could then save it as a .brep file and in a new .geo file use this .brep file in </div><div id="yui_3_16_0_1_1424339378984_6124" dir="ltr">the merge"file.brep" line. Either way, you should now have geometry without any duplicate geometric </div><div id="yui_3_16_0_1_1424339378984_6295" dir="ltr">entity problems.</div><div id="yui_3_16_0_1_1424339378984_6146" dir="ltr"><br></div><div id="yui_3_16_0_1_1424339378984_6240" dir="ltr">2) load the .step file exported from CAD into gmsh using File>Open (not via a .geo file with the merge line)<br>save it as a .geo file in the GEO options make sure NONE of the check boxes are ticked. I know this is not</div><div id="yui_3_16_0_1_1424339378984_6239" dir="ltr">recommended but for my geometry it seems to work and lets me proceed.<br>Load this .geo file and click coherence to remove the duplicate geometric objects then reload.</div><div id="yui_3_16_0_1_1424339378984_6256" dir="ltr"><br></div><div id="yui_3_16_0_1_1424339378984_6255" dir="ltr"><br></div><div id="yui_3_16_0_1_1424339378984_5940" dir="ltr">No guarantee that either will work for all possible geometries ;-( </div><div id="yui_3_16_0_1_1424339378984_6325" dir="ltr"><br></div><div id="yui_3_16_0_1_1424339378984_6326" dir="ltr">HTH.</div><div id="yui_3_16_0_1_1424339378984_6339" dir="ltr">Regards</div><div id="yui_3_16_0_1_1424339378984_6340" dir="ltr">Mark</div><div id="yui_3_16_0_1_1424339378984_5937"><br> </div><div id="yui_3_16_0_1_1424339378984_5691" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_1_1424339378984_5690" style="font-family: HelveticaNeue, Helvetica Neue, Helvetica, Arial, Lucida Grande, sans-serif; font-size: 16px;"> <div id="yui_3_16_0_1_1424339378984_5689" dir="ltr"> <hr size="1" id="yui_3_16_0_1_1424339378984_5847"> <font id="yui_3_16_0_1_1424339378984_5692" face="Arial" size="2"> <b id="yui_3_16_0_1_1424339378984_5849"><span id="yui_3_16_0_1_1424339378984_5848" style="font-weight: bold;">From:</span></b> Christophe Geuzaine <cgeuzaine@ulg.ac.be><br> <b><span style="font-weight: bold;">To:</span></b> Mark Smith <piedycat@yahoo.com> <br> <b id="yui_3_16_0_1_1424339378984_5851"><span id="yui_3_16_0_1_1424339378984_5850" style="font-weight: bold;">Sent:</span></b> Wednesday, February 18, 2015 4:38 PM<br> <b id="yui_3_16_0_1_1424339378984_5853"><span id="yui_3_16_0_1_1424339378984_5852" style="font-weight: bold;">Subject:</span></b> Re: step import error<br> </font> </div> <div class="y_msg_container" id="yui_3_16_0_1_1424339378984_5693"><br><br clear="none">> On 17 Feb 2015, at 11:46, Mark Smith <<a id="yui_3_16_0_1_1424339378984_6133" href="mailto:piedycat@yahoo.com" shape="rect" ymailto="mailto:piedycat@yahoo.com">piedycat@yahoo.com</a>> wrote:<br clear="none">> <br clear="none">> Hi Christophe,<br clear="none">> I agree that the file imports OK but the inner surfaces (those that separate the volumes) have duplicate<br clear="none">> surfaces overlying one another so when you 2D mesh you get over lapping meshes?<br clear="none">> The defined physical groups>surfaces numbers do not change position now on reload which is good.<br clear="none">> Using the 3D mesh with Elmer for a CFD simulation produces incorrect unreasonable results<br clear="none">> as would be expected, if I get rid of the duplicate surfaces using GiD which<br clear="none">> for this model can be used in the evaluation mode, exported as iges, read into GMSH and exported as<br clear="none">> brep then all the problems go away.<br clear="none">> The previous example I sent, the cut and merge faces option sorted the duplicate faces/lines/points<br clear="none">> out but not so with the split_pipe.step I sent you?<br clear="none">> <br clear="none"><br clear="none">Yes, it screwed up the topology somehow... I guess for now the only robust solution is to eliminate the duplicates using a "real" CAD kernel, and only import the correct STEP into Gmsh.<br clear="none"><br clear="none">Christophe<br clear="none"><br clear="none">> Regards<br clear="none">> Mark<br clear="none">> From: Christophe Geuzaine <<a id="yui_3_16_0_1_1424339378984_6411" href="mailto:cgeuzaine@ulg.ac.be" shape="rect" ymailto="mailto:cgeuzaine@ulg.ac.be">cgeuzaine@ulg.ac.be</a>><br clear="none">> To: Mark Smith <<a href="mailto:piedycat@yahoo.com" shape="rect" ymailto="mailto:piedycat@yahoo.com">piedycat@yahoo.com</a>> <br clear="none">> Sent: Monday, February 16, 2015 6:56 PM<br clear="none">> Subject: Re: step import error<br clear="none">> <br clear="none">> <br clear="none">> > On 16 Feb 2015, at 13:44, Mark Smith <<a href="mailto:piedycat@yahoo.com" shape="rect" ymailto="mailto:piedycat@yahoo.com">piedycat@yahoo.com</a>> wrote:<br clear="none">> > <br clear="none">> > Hi Christophe,<br clear="none">> > gmsh still has step file import problems as I discovered with the simple geometry attached.<br clear="none">> > with cut and merge faces checked, I get the following warning & 1 face and volume is missing:<br clear="none">> > OCC STL triangulation of surface 11 failed.<br clear="none">> > <br clear="none">> > Any ideas?<br clear="none">> <br clear="none">> Hi Mark - No... "Cut & Merge" is really experimental; the file imports fine without it...<br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> > Thanks in advance.<br clear="none">> > Regards<br clear="none">> > Mark<br clear="none">> <br clear="none">> > <split_pipe.STEP><br clear="none">> <br clear="none">> -- <br clear="none">> Prof. Christophe Geuzaine<br clear="none">> University of Liege, Electrical Engineering and Computer Science <br clear="none">> <a href="http://www.montefiore.ulg.ac.be/~geuzaine" target="_blank" shape="rect">http://www.montefiore.ulg.ac.be/~geuzaine</a><div class="qtdSeparateBR"><br><br></div><div class="yqt0568873448" id="yqtfd84512"><br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none">> <br clear="none"><br clear="none">-- <br clear="none">Prof. Christophe Geuzaine<br clear="none">University of Liege, Electrical Engineering and Computer Science <br clear="none"><a href="http://www.montefiore.ulg.ac.be/~geuzaine" target="_blank" shape="rect">http://www.montefiore.ulg.ac.be/~geuzaine</a><br clear="none"><br clear="none"><br clear="none"></div><br><br></div> </div> </div> </div></body></html>