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<p class="MsoNormal">The following test program, which generates a helical pipe by extruding a disk along a spline.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">When the number of turns of the helix is 4, it generates an attractive helix, and 3D-mesh creates an attractive mesh.</p>
<p class="MsoNormal">When the number of turns of the helix is 5, it generates an attractive helix, and 3D mesh crashes gmsh.</p>
<p class="MsoNormal">When the number of turns is 12, the helix is ugly, and 3D mesh crashes gmsh.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">I would very much appreciate your insight into diagnosing the error.</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">SetFactory("OpenCASCADE");</p>
<p class="MsoNormal">bottom = 0;</p>
<p class="MsoNormal">steps = 3000;</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">bodyturns = 12;</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">pitch = 5; // vertical mm/turn</p>
<p class="MsoNormal">turnsteps =20; // reference points for each turn of the helix</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">radius = 2.5;</p>
<p class="MsoNormal">lc = 0.05;</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">argmult = 2*Pi/pitch ;</p>
<p class="MsoNormal">nsteps = bodyturns*turnsteps;</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">For ii In {0:nsteps}</p>
<p class="MsoNormal"> zpos = (pitch/turnsteps) * ii;</p>
<p class="MsoNormal"> xpos = radius*Cos(argmult*(zpos));</p>
<p class="MsoNormal"> ypos = radius*Sin(argmult*(zpos));</p>
<p class="MsoNormal"> Point(ii) = {xpos, ypos, zpos, lc};</p>
<p class="MsoNormal">EndFor</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Disk(1000) = {radius, 0, 0, 0.5};</p>
<p class="MsoNormal">jcoef = -pitch/Sqrt(pitch^2 + 4 * Pi^2);</p>
<p class="MsoNormal">kcoef = (2 * Pi)/Sqrt(pitch^2 + 4 * Pi^2);</p>
<p class="MsoNormal">Rotate {{-1, 0, 0}, {radius,0,0}, Asin(kcoef)} { Surface{1000}; }</p>
<p class="MsoNormal">Spline(2000) = {0:nsteps};</p>
<p class="MsoNormal">Wire(3000) = {2000};</p>
<p class="MsoNormal">Extrude { Surface{1000}; } Using Wire{3000}</p>
<p class="MsoNormal"><o:p> </o:p></p>
<p class="MsoNormal">Sent from <a href="https://go.microsoft.com/fwlink/?LinkId=550986">
Mail</a> for Windows 10</p>
<p class="MsoNormal"><o:p> </o:p></p>
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