[Gmsh] Extrusion produces an incorrect number of layers
Felix Salazar
felix.salazar at polymtl.ca
Wed Nov 6 00:48:37 CET 2013
In my previous message, I said 8 layers in the 1st and 3rd extrusion, but
they are actually 10. The rest it's still valid
------------------------------------
* Félix Salazar**felix.salazar at polymtl.ca <felix.salazar at polymtl.ca>*
Étudiant au doctorat - PhD Student
*École Polytechnique de Montréal*
* LADYF*
Lab. de dynamique des fluides
(514) 340 4711 ext 2489
Local: C-318.21.3
------------------------------------
On Tue, Nov 5, 2013 at 6:17 PM, Felix Salazar <felix.salazar at polymtl.ca>wrote:
> I'm building a cylindrical geometry using extrusion, and managed to put a
> Bump like layer distribution, using a modified version of an example given
> by Christophe in the mailing list. (It's actually a double progression).
> The script is not clean, and probably not very efficient, but it works. Or
> at least, it seems to work.
>
> Part of my geometry includes a simple extrusion of a circle 3 times, with
> different length and layer distribution. The 1st and 3rd section should be
> identical. However, Gmsh is giving at least an additional layer in the 3rd
> section, with the normal in the opposite direction of the rest of extrusion.
>
> Here's the simplified script reproducing the problem. I tested it in Gmsh
> 2.8, 2.6 and 2.5, with the same result.
>
> //==== BEGIN OF .GEO
> /*==============================*/
> /*==== Geometric parameters ====*/
> /*==============================*/
> D1 = 1;
> D2 = 1.00;
> L = D1;
> BL = 0.5;
> //==============================
> factorRefinement = 1.0;
> core = 4;
> radial = Ceil((R1+R2/4)/(BL/core));
> Rprog = 0.9;
> lc = R1*(Pi/2)/core;
> z1 = Ceil(factorRefinement*(L)/lc);
> z2 = Ceil(factorRefinement*(L/2)/lc);
> Zbump = 1.35;
> Geometry.ExtrudeReturnLateralEntities = 0;
> //==============================
> // LIST OF POINTS
> Point(1) = {0, 0, 0};
> Point(2) = {0, R1, 0};
> Point(3) = {0, BL*R1, 0};
>
> rot1[] = Rotate { {0,0,1}, {0,0,0}, Pi/2} {
> Duplicata{Point{2,3};}
> };
> rot2[] = Rotate { {0,0,1}, {0,0,0}, Pi/2} {
> Duplicata{Point{rot1[0],rot1[1]};}
> };
> rot3[] = Rotate { {0,0,1}, {0,0,0}, Pi/2} {
> Duplicata{Point{rot2[0],rot2[1]};}
> };
>
> Circle(1) = {2, 1, rot1[0]};
> Circle(2) = {rot1[0],1,rot2[0]};
> Circle(3) = {rot2[0],1,rot3[0]};
> Circle(4) = {rot3[0],1,2};
> Line(5) = {3, rot1[1]};
> Line(6) = {rot1[1],rot2[1]};
> Line(7) = {rot2[1],rot3[1]};
> Line(8) = {rot3[1],3};
> Transfinite Line {1,2,3,4,5,6,7,8} = Ceil(factorRefinement*core+1);
> Line(9) = {3,2};
> Line(10) = {rot1[1],rot1[0]};
> Line(11) = {rot2[1],rot2[0]};
> Line(12) = {rot3[1],rot3[0]};
> Transfinite Line {9,10,11,12} = Ceil(factorRefinement*radial+1) Using
> Progression Rprog;
>
> Line Loop(5) = {5,6,7,8};
> Plane Surface(5) = {-5};
> Line Loop(1) = {1,-10,-5,9};
> Plane Surface(1) = {-1};
> Line Loop(2) = {2,-11,-6,10};
> Plane Surface(2) = {-2};
> Line Loop(3) = {3,-12,-7,11};
> Plane Surface(3) = {-3};
> Line Loop(4) = {4,-9,-8,12};
> Plane Surface(4) = {-4};
> Transfinite Surface {5,1,2,3,4};
>
> //======================
> Function BumpExtrude
> n0 = Ceil(n/2);
> nN = n - n0;
> a0= (n0/n)*(r - 1) / ((r^n0) - 1);
> aN= (nN/n)*((1/r) - 1) / (((1/r)^nN) - 1);
>
> one[0] = 1;
> layer[0] = a0;
> Printf("%g %g",0,layer[0]);
> For i In {1:n-1}
> one[i] = 1;
> layer[i] = layer[i-1] + a0 * r^i;
> If(i>=n0)
> layer[i] = layer[i-1] + aN * (1/r)^(i-n0);
> EndIf
> Printf("%g %g",i,layer[i]);
> EndFor
> Return
> //======================
> n = 3*(z2+1) - 1; // number of intervals
> r = Zbump; // Bump progression
> Call BumpExtrude;
> Extrude {0,0,-L/2} {
> Surface{1,2,3,4,5}; Layers{one[], layer[]}; Recombine;
> }
> //======================
> n = 3*(z1+1) - 1; // number of intervals
> r = Zbump; // Bump progression
> Call BumpExtrude;
> Extrude {0,0,-L} {
> Surface{-34,-56,-78,-100,-122}; Layers{one[], layer[]}; Recombine;
> }
> //======================
> n = 3*(z2+1) - 1; // number of intervals
> r = Zbump; // Bump progression
> Call BumpExtrude;
> Extrude {0,0,-L/2} {
> Surface{-144,-166,-188,-210,-232}; Layers{one[], layer[]}; Recombine;
> }
> //=====OPTIONS=====
> Geometry.AutoCoherence = 1;
> Geometry.CopyMeshingMethod = 1;
> Geometry.LightTwoSide = 0;
> Geometry.Lines = 1;
> Geometry.LineNumbers = 1;
> Geometry.Points = 0;
> Geometry.PointNumbers = 0;
> Geometry.Surfaces = 1;
> Geometry.SurfaceNumbers = 1;
> Geometry.Volumes = 0;
> Mesh.Algorithm = 6;
> Mesh.Algorithm3D = 4;
> Mesh.CharacteristicLengthExtendFromBoundary = 0;
> Mesh.CharacteristicLengthFromCurvature = 0;
> Mesh.CharacteristicLengthFromPoints = 0;
> Mesh.ColorCarousel = 2;
> Mesh.LabelType = 2;
> Mesh.ElementOrder = 2;
> Mesh.Light = 0;
> Mesh.LightTwoSide = 0;
> Mesh.Lines = 0;
> Mesh.Optimize = 0;
> Mesh.RandomFactor = 1e-6;
> Mesh.ReverseAllNormals = 1;
> Mesh.SaveElementTagType = 2;
> Mesh.Format = 30;
> Mesh.SecondOrderIncomplete = 0;
> Mesh.SecondOrderLinear = 0;
> Mesh.Smoothing = 0;
> Mesh.SurfaceFaces = 1;
> Mesh.VolumeEdges = 0;
> Mesh.RecombineAll = 1;
> Mesh.Color.Zero = {177,149,255};
> Mesh.Color.One = {255,6,0};
> Mesh.Color.Two = {0,255,71};
> Mesh.Color.Three = {0,54,255};
> Mesh.Color.Four = {255,155,0};
> Mesh.Color.Six = {0,255,184};
> Mesh.Color.Seven = {195,255,152};
> Mesh.Color.Eight = {255,35,247};
> //END OF .GEO
>
> Note that the parameters for the first and 3rd extrusions are identical,
> with the exception of the surface list.
>
> I added a couple of lines, to print into console the position of the
> layers. The 1st and 3rd layer, with the parameters of the example, have 8
> layers according to the printed info, but the mesh on the screen shows
> something different.
>
> I tried tweaking some of the meshing options, without success. Displaying
> the normals show that the extra layer is somewhat "inverted" if compared
> with the others.
>
> Is there anything wrong with my Mesh options? Or the script has an error
> that I can't see. Any help is appreciated.
>
> Thanks,
>
> ------------------------------------
>
> * Félix Salazar**felix.salazar at polymtl.ca <felix.salazar at polymtl.ca>*
> Étudiant au doctorat - PhD Student
> *École Polytechnique de Montréal*
> * LADYF*
> Lab. de dynamique des fluides
> (514) 340 4711 ext 2489
> Local: C-318.21.3
> ------------------------------------
>
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