what's wrong with using Gmsh' physical entities for defining boundary conditions?<div><br></div><div>btw, the answer to what you asked is: export the model to brep and you will get all the information there. Look for the brep format description in the opencascade documentation.</div><div><br></div><div><div dir="auto"><div class="gmail_quote"><div dir="ltr">On Fri, Aug 17, 2018, 13:46 Pieter Reumers <<a href="mailto:pieter.reumers@kuleuven.be">pieter.reumers@kuleuven.be</a>> wrote:<br></div><blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
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<p class="MsoNormal"><span lang="NL-BE">Dear all,<u></u><u></u></span></p>
<p class="MsoNormal"><span lang="NL-BE"><u></u> <u></u></span></p>
<p class="MsoNormal">I’m trying to get access to the full geometry of a certain model created using gmsh. For example, consider the following *.geo file:
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Point(1)={0, 0, 0}; <u></u><u></u></p>
<p class="MsoNormal">Point(2)={1, 0, 0};<u></u><u></u></p>
<p class="MsoNormal">Point(3)={0, 1, 0}; <u></u><u></u></p>
<p class="MsoNormal">Circle(1)={2,1,3}; <u></u><u></u></p>
<p class="MsoNormal">Line(2)={2,3};<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">This *.geo file creates a quarter circle and a straight line. When using the Mesh.SaveTopology option, all entities are saved in the $Entities … $EndEntities section:<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">$Entities<u></u><u></u></p>
<p class="MsoNormal">3 2 0 0<u></u><u></u></p>
<p class="MsoNormal">1 0 // Point 1<u></u><u></u></p>
<p class="MsoNormal">2 0 // Point 2<u></u><u></u></p>
<p class="MsoNormal">3 0 // Point 3<u></u><u></u></p>
<p class="MsoNormal">1 2 2 3 0 // Line 1 (=circle)<u></u><u></u></p>
<p class="MsoNormal">2 2 2 3 0 // Line 2<u></u><u></u></p>
<p class="MsoNormal">$EndEntities <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">As you can see, lines 1 and 2 seem to be identical entities, while in reality they are not. Line 1 is a quarter circle, while line 2 is a straight line. Is there a way to export the full geometry/topology information from gmsh at the moment?
Thus, for a circle, this would be three points (the input points provided to the Circle command). My goal is to use gmsh as a mesh generator and couple it to an existing MATLAB finite element solver. Extracting the precise topology from gmsh allows for the
easy definition of boundary conditions (e.g. distributed load on a circular line segment or pressure on a curved surface).
<u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Thanks in advance. <u></u><u></u></p>
<p class="MsoNormal"><u></u> <u></u></p>
<p class="MsoNormal">Kind regards,<u></u><u></u></p>
<p class="MsoNormal">Pieter Reumers<u></u><u></u></p>
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</blockquote></div></div></div>-- <br><div dir="ltr" class="gmail_signature" data-smartmail="gmail_signature"><div dir="ltr"><div><div>--<br></div>jeremy theler<br></div><a href="http://www.seamplex.com">www.seamplex.com</a><br></div></div>