<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>
          <div title="MDH:PGRpdj48ZGl2PllvdSBjb3VsZCBkZWxldGUgdGhlIHZvbHVtZSBvZiB0aGUgY3lsaW5kZXIgeW91J3ZlIGNyZWF0ZWQgYnkgbWVhbnMgb2YgZXh0cnVzaW9uIGFuZCB0aGVuIGRlbGV0ZSBvbmUgb2Yg
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            dmUgYSB3b3JraW5nIG1lc2guPGJyPgo8ZGl2Pjxicj48L2Rpdj4=" style="min-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><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" target="_blank">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: <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>