[Gmsh] Problem of Conformal Meshing at Volume boundaries

SAHA, SUDIPTA sahas at email.sc.edu
Mon Aug 3 22:11:59 CEST 2020

```Typically you need to treat conforming geometry before you treat mesh. Try adding Coherence; in the script prior to meshing. If you could send the geo and log file I can check. My email is sahas at cec.sc.edu

__

Best Regards
Sudipta Saha, MS, EIT
Spent Fuel Modeling Intern, Idaho National Laboratory

PhD Candidate in Mechanical Engineering
Reacting System and Advanced Energy Research Lab
[cid:500b8551-0821-42f0-8b09-bb908bc10418]

________________________________
From: gmsh <gmsh-bounces at ace20.montefiore.ulg.ac.be> on behalf of Patrick Tsui <pcptsui at gmail.com>
Sent: Monday, August 3, 2020 12:13 PM
To: gmsh at onelab.info <gmsh at onelab.info>
Subject: [Gmsh] Problem of Conformal Meshing at Volume boundaries

Dear All,

I am having trouble getting conformal meshing at boundaries of volumes. I tried a good number of suggestions found online but failed. For the simple codes tested (listed below and attached), 104 errors appeared. Gmsh 4.7.0 on Ubuntu 19.10 were used. Any help would be highly appreciated.

// Code begins ------------------------------------------------------------------------

mm2m = 0.001;
i2m = 0.0254;
Geometry.AutoCoherence = 1;
Mesh.CharacteristicLengthMin = 0.125*i2m;
Mesh.CharacteristicLengthMax = 0.250*i2m;
Geometry.Tolerance = 0.01*mm2m;
lc  = 0.125*i2m;

a  = 2.0 * i2m;
p1=newp; Point(p1) = { a, 0.0,  a, lc};
p2=newp; Point(p2) = {-a, 0.0,  a, lc};
p3=newp; Point(p3) = {-a, 0.0, -a, lc};
p4=newp; Point(p4) = { a, 0.0, -a, lc};
l1=newl; Line(l1) = {p1, p2};
l2=newl; Line(l2) = {p2, p3};
l3=newl; Line(l3) = {p3, p4};
l4=newl; Line(l4) = {p4, p1};
ll1=newll; Curve Loop(ll1) = {l1, l2, l3, l4};
s1=news; Plane Surface(s1)={ll1};
hh = 0.5*i2m;
id[] = Extrude {0,hh,0} { Surface{s1}; Layers{ 1 }; Recombine; };
v1 = id[1];

p5=newp; Point(p5) = { a/2, 0.0,  a/2, lc};
p6=newp; Point(p6) = {-a/2, 0.0,  a/2, lc};
p7=newp; Point(p7) = {-a/2, 0.0, -a/2, lc};
p8=newp; Point(p8) = { a/2, 0.0, -a/2, lc};
l5=newl; Line(l5) = {p5, p6};
l6=newl; Line(l6) = {p6, p7};
l7=newl; Line(l7) = {p7, p8};
l8=newl; Line(l8) = {p8, p5};
Point {p5,p6,p7,p8} In Surface{s1};
Line {l5,l6,l7,l8} In Surface{s1};

ll2=newll; Curve Loop(ll2) = {l5, l6, l7, l8};
s2=news; Plane Surface(s2)={ll2};
id[] = Extrude {0,-hh,0} { Surface{s2}; Layers{ 1 }; Recombine; };
v2 = id[1];

Surface {s2} In Volume{v1};

v() = BooleanFragments{ Volume{v1}; Delete;}{ Volume{v2}; Delete;};
n=#v();
For i In {0:n-1}
Printf("v(%g) = %g",i,v(i));
EndFor

Mesh 3;
Coherence Mesh;

// Code ends ------------------------------------------------------------------------

Sincerely,

PT
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