<div dir="ltr"><div><div><div><div>If you change the lines in your file after ```//Using compound volumes``` to the ones from my previous mail, you should get the same result. <br></div>From the looks of your screenshot, it would seem the bottom half is not defined as a volume. I got it automatically as a volume though, from the extrusion command. Odd.<br>
<br></div>After my first reply, I've looked more into those GRegion Compound errors, and have seen that they're a recurring problem on the mailing list when trying to use Compound Volume, but so far no solutions have been given/found. I'm hoping an answer will come one day though.<br>
<br></div>The only other solution I see (at the moment, due to the failing compound volumes) to ensure the mesh is "continuous" across the interface, is simply not to have the interface at all. So manually fleshing out the geometry, point by point, line by line (okay, you can extrude some points and lines of course) and then definining a single volume by selecting the faces of the cylinder and the box. So this comes back to your original question:<br>
>> 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></div>At the moment: no. Unless you don't mind that artificial interface.<br><div class="gmail_extra"><br><br><div class="gmail_quote">2014-09-02 21:13 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 Oliver,<br>
Thanks for your response. I had also tried the variation that you
sent me. The issue is that I don't want to have the flat surface
that is interfacing the two volumes. I'd like the mesh to be
continuous across that interface.<br>
<br>
Also, when following your suggestion, I still cannot get the same
exact mesh as you did. Please see the attached screenshot. <br>
<br>
Is there any other thoughts on how to get the results I'm aiming
for?<br>
<br>
Thank you,<br>
Omid<div><div class="h5"><br>
<br>
<div>On 14-08-28 06:34 PM, Oliver Willekens
wrote:<br>
</div>
<blockquote type="cite">
<div dir="ltr">
<div>
<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-wrap;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>
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</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><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>
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<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: <a href="tel:%2B32%209%20264.89.51" value="+3292648951" target="_blank">+32 9 264.89.51</a>
</p>
</div>
</blockquote>
<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>
</div></div></div>
</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></div>