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GMSH: 2D axisymmetric structured mesh

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Old   April 29, 2020, 15:10
Default GMSH: 2D axisymmetric structured mesh
  #1
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Mary
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Hi,

I want to create a structured mesh for my 2D axisymmetric case with gmsh. The difference between the 2D and 2D axisymmetric lies where
Code:
   
Extrude {0,0,Z} {
      Surface{14,12,16}; Layers{1}; Recombine;
    }
    Coherence;
becomes
Code:
        Rotate {{1, 0, 0}, {0, 0, 0}, -angle/2} {
            Surface{12,14,16};
        }
       
        Extrude {{1, 0, 0}, {0, 0, 0}, angle} {
        Surface{12,14,16};  Layers{1}; Recombine;
        }Coherence;
My 2D case is structured (figure 2D.png) while my 2D axisym becomes highly unstructured (figure 2D_axisym.png).


The .geo file specifying the features of the mesh is exactly the same expect the part that I mentioned above. I read earlier that by indicating the surfaces to be recombined as follows:
Code:
Transfinite Surface {14,12,16};
Recombine Surface {14,12,16};
we enforce the mesh to become structured. However, despite the fact the I recombine the surfaces, the mesh is unstructured in 2D axisymmetric case.

Does anyone have a clue to help me ?

Thanks in advance,
Mary
Attached Images
File Type: png 2D.png (6.5 KB, 32 views)
File Type: png 2D_axisym.png (11.7 KB, 33 views)
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Old   May 2, 2020, 05:20
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Mary
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No one can help me ?
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Old   September 6, 2020, 05:00
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dinesh Choudhary
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I am having same issue mesh is getting unstructured does anyone have solution for this....?
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Old   November 5, 2020, 19:17
Default Structured annular 2D mesh in gmsh
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Mark Stock
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I've been working on this today, and here is my solution: don't use Extrude, keep it all 2D. This generates a 2D structured annular mesh of quads.
Code:
xc = 0.0;
yc = 0.0;
r0 = 0.5;
r1 = 1.0;
ncirc = 1.65*r0/0.05;
nrad = (r1-r0)/0.05;

Point(1) = {xc,    yc,    0};
Point(2) = {xc+r0, yc,    0};
Point(3) = {xc,    yc+r0, 0};
Point(4) = {xc-r0, yc,    0};
Point(5) = {xc,    yc-r0, 0};

Point(6) = {xc+r1, yc,    0};
Point(7) = {xc,    yc+r1, 0};
Point(8) = {xc-r1, yc,    0};
Point(9) = {xc,    yc-r1, 0};
Point(10)= {xc,    yc,    0};

Circle(1) = {2,1,3};
Circle(2) = {3,1,4};
Circle(3) = {4,1,5};
Circle(4) = {5,1,2};

Circle(5) = {6,10,7};
Circle(6) = {7,10,8};
Circle(7) = {8,10,9};
Circle(8) = {9,10,6};
Transfinite Curve{1:8} = ncirc;

Line(11) = {2, 6};
Line(12) = {3, 7};
Line(13) = {4, 8};
Line(14) = {5, 9};
Transfinite Curve{11:14} = nrad Using Progression 1.1;

Curve Loop(11) = {11, 5, -12, -1};
Plane Surface(12) = {11};
Transfinite Surface{12};
Recombine Surface{12};

Curve Loop(13) = {12, 6, -13, -2};
Plane Surface(14) = {13};
Transfinite Surface{14};
Recombine Surface{14};

Curve Loop(15) = {13, 7, -14, -3};
Plane Surface(16) = {15};
Transfinite Surface{16};
Recombine Surface{16};

Curve Loop(17) = {14, 8, -11, -4};
Plane Surface(18) = {17};
Transfinite Surface{18};
Recombine Surface{18};
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