<div dir="ltr"><div style class="markdown-here-wrapper"><p style="margin:1.2em 0px!important">You could delete the volume of the cylinder you’ve created by means of extrusion and then delete one of the cylinder’s flat surfaces using the <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">Delete</code> command. However, it won’t give you what you want, because the box “holding the cylinder” will be unaware of the presence of the cylindrical hole.</p>
<p style="margin:1.2em 0px!important">I tried this:</p>
<pre style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;font-size:1em;line-height:1.2em;margin:1.2em 0px"><code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline;white-space:pre;overflow:auto;border-radius:3px;border:1px solid rgb(204,204,204);padding:0.5em 0.7em;display:block!important;display:block;padding:0.5em;color:rgb(51,51,51);background:none repeat scroll 0% 0% rgb(248,248,255)">Plane Surface(1) = {1, 2}; // square minus the circle
out1[] = Extrude {0.0, 76.2, 0.0}{Surface{1};};
Plane Surface(2) = {1};
out2[] = Extrude {0.0, -76.2, 0.0} {Surface{2};};
</code></pre><p style="margin:1.2em 0px!important">Which results in the 2D mesh you find in the attachment. Perhaps this is what you’re looking for?</p>
<p style="margin:1.2em 0px!important">I also tried combining those two volumes using <code style="font-size:0.85em;font-family:Consolas,Inconsolata,Courier,monospace;margin:0px 0.15em;padding:0px 0.3em;white-space:pre-wrap;border:1px solid rgb(234,234,234);background-color:rgb(248,248,248);border-radius:3px;display:inline">Compound Volume(4) = {out1[1], out2[1]};</code>, but like you, I got GRegion Compound errors. Probably some basic restriction from triangulations I’m overlooking. This only means your 3D meshes will be clearly stopped at a flat interface about half-way through those two boxes, but you’ll still have a 3D mesh. I was hoping that the Compound Volume would make some tetras across this boundary though… But with the above lines, you’ll have a working mesh.</p>
<div title="MDH:PGRpdj48ZGl2PllvdSBjb3VsZCBkZWxldGUgdGhlIHZvbHVtZSBvZiB0aGUgY3lsaW5kZXIgeW91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" style="height:0;font-size:0em;padding:0;margin:0"></div></div></div><div class="gmail_extra"><br><br><div class="gmail_quote">2014-08-28 17:08 GMT+02:00 Omid Mahabadi <span dir="ltr"><<a href="mailto:omid.mahabadi@geomechanica.com" target="_blank">omid.mahabadi@geomechanica.com</a>></span>:<br>
<blockquote class="gmail_quote" style="margin:0 0 0 .8ex;border-left:1px #ccc solid;padding-left:1ex">
<div bgcolor="#FFFFFF" text="#000000">
Hi Christophe and Gmsh team,<br>
I've been trying to model a simple cube with a cylindrical hole that
is NOT through-going (i.e., its depth is smaller than the depth of
the cube), as shown in the attached picture. The Extrude command
doesn't seem to work since it will extrude both surfaces (exterior
and interior -- hole) at the same time. I know I can define all the
surfaces, surface loops, and volumes manually, but is there a better
way of defining something like this in Gmsh? <br>
<br>
I also tried to use the Compound Volume command by first defining
two volumes from Extrude and then trying to combine them but I'm
getting errors for the Compound Volume visualization (Error: Cannot
evaluate bounds on GRegion Compound) and when I mesh the geometry,
the actual shared interfaces are still existing, although by the
notion of compound from the documentation, the internal interfaces
should be neglected. Here is the geometry file:<br>
<blockquote>// Characteristic length (==> element size)<br>
cl_external = 25;<br>
cl_excavation = 5;<br>
<br>
// External boundaries<br>
Point(1) = {-127, 0.0, -127, cl_external};<br>
Point(2) = {+127, 0.0, -127, cl_external};<br>
Point(3) = {+127, 0.0, +127, cl_external};<br>
Point(4) = {-127, 0.0, +127, cl_external};<br>
Line(1) = {1, 2};<br>
Line(2) = {2, 3};<br>
Line(3) = {3, 4};<br>
Line(4) = {4, 1};<br>
Line Loop(1) = {1, 2, 3, 4};<br>
<br>
// Excavation boundaries<br>
Point(5) = {0.0, 0.0, 0.0, cl_excavation};<br>
Point(6) = {19.05, 0.0, 0.0, cl_excavation};<br>
Point(7) = {0.0, 0.0, 19.05, cl_excavation};<br>
Point(8) = {-19.05, 0.0, 0.0, cl_excavation};<br>
Point(9) = {0.0, 0.0, -19.05, cl_excavation};<br>
Circle(5) = {6, 5, 7};<br>
Circle(6) = {7, 5, 8};<br>
Circle(7) = {8, 5, 9};<br>
Circle(8) = {9, 5, 6};<br>
Line Loop(2) = {5, 6, 7, 8};<br>
<br>
//Using compound volumes<br>
Plane Surface(1) = {1};<br>
out1[] = Extrude {0.0, 76.2, 0.0}{Surface{1};};<br>
<br>
Plane Surface(2) = {1};<br>
out2[] = Extrude {0.0, -76.2, 0.0}{Surface{2};};<br>
<br>
Compound Volume(3) = {1, 2};<br>
</blockquote>
<br>
I also tried to create the geometry in CAD software and imported it
as iges, brep or step formats but for reason the hole is not there
completely. See for instances the iges file attached.<br>
<br>
Can you kindly shed some light here? Am I doing something wrong? Or
are there Gmsh tricks/commands that I can use to achieve my goal?<br>
<br>
Thank you,<br>
Omid<span class="HOEnZb"><font color="#888888"><br>
<br>
<pre cols="72">--
Omid Mahabadi, Ph.D.
Geomechanica, Inc.
<a href="http://www.geomechanica.com/" target="_blank">http://www.geomechanica.com/</a>
Tel : <a href="tel:%2B1-647-478-9767" value="+16474789767" target="_blank">+1-647-478-9767</a>
Cell: <a href="tel:%2B1-416-824-2408" value="+14168242408" target="_blank">+1-416-824-2408</a>
</pre>
</font></span></div>
<br>_______________________________________________<br>
gmsh mailing list<br>
<a href="mailto:gmsh@geuz.org">gmsh@geuz.org</a><br>
<a href="http://www.geuz.org/mailman/listinfo/gmsh" target="_blank">http://www.geuz.org/mailman/listinfo/gmsh</a><br>
<br></blockquote></div><br><br clear="all"><br>-- <br>
Oliver Willekens<br>
PhD Student <br>
<a href="https://lcp.elis.ugent.be/" target="_blank"><img src="http://lcp.elis.ugent.be/sites/lcp.elis.ugent.be/files/logo.jpg" alt="LCP group logo" style="float:left;margin-right:20px;margin-top:20px"></a>
<p style="margin-top:20px">
Liquid Crystals & Photonics Group <br>
Sint- Pietersnieuwstraat 41 <br>
9000 Gent <br>
Phone: +32 9 264.89.51
</p>
</div>