Tutorial 3
Extruded meshes, options
import gmshgmsh.initialize()gmsh.model.add("t3")Copied from tutorial 1:
lc = 1e-2
gmsh.model.geo.addPoint(0, 0, 0, lc, 1)
gmsh.model.geo.addPoint(.1, 0, 0, lc, 2)
gmsh.model.geo.addPoint(.1, .3, 0, lc, 3)
gmsh.model.geo.addPoint(0, .3, 0, lc, 4)
gmsh.model.geo.addLine(1, 2, 1)
gmsh.model.geo.addLine(3, 2, 2)
gmsh.model.geo.addLine(3, 4, 3)
gmsh.model.geo.addLine(4, 1, 4)
gmsh.model.geo.addCurveLoop([4, 1, -2, 3], 1)
gmsh.model.geo.addPlaneSurface([1], 1)
gmsh.model.geo.synchronize()
gmsh.model.addPhysicalGroup(0, [1, 2], 1)
gmsh.model.addPhysicalGroup(1, [1, 2], 2)
gmsh.model.addPhysicalGroup(2, [1], 6)
gmsh.model.setPhysicalName(2, 6, "My surface")As in Tutorial 2, we plan to perform an extrusion along the z axis. But here, instead of only extruding the geometry, we also want to extrude the 2D mesh. This is done with the same extrude() function, but by specifying element 'Layers' (2 layers in this case, the first one with 8 subdivisions and the second one with 2 subdivisions, both with a height of h/2). The number of elements for each layer and the (end) height of each layer are specified in two vectors:
h = 0.1
angle = 90.
ov = gmsh.model.geo.extrude([(2,1)], 0, 0, h, [8,2], [0.5,1])6-element Array{Tuple{Int32,Int32},1}:
(2, 28)
(3, 1)
(2, 15)
(2, 19)
(2, 23)
(2, 27)The extrusion can also be performed with a rotation instead of a translation, and the resulting mesh can be recombined into prisms (we use only one layer here, with 7 subdivisions). All rotations are specified by an an axis point (-0.1, 0, 0.1), an axis direction (0, 1, 0), and a rotation angle (-Pi/2):
ov = gmsh.model.geo.revolve([(2,28)], -0.1,0,0.1, 0,1,0, -pi/2, [7])6-element Array{Tuple{Int32,Int32},1}:
(2, 50)
(3, 2)
(2, 37)
(2, 41)
(2, 45)
(2, 49)Using the built-in geometry kernel, only rotations with angles < Pi are supported. To do a full turn, you will thus need to apply at least 3 rotations. The OpenCASCADE geometry kernel does not have this limitation.
A translation(-2*h, 0, 0) and a rotation((0,0.15,0.25), (1,0,0), Pi/2) can also be combined to form a "twist". The last (optional) argument for the extrude() and twist() functions specifies whether the extruded mesh should be recombined or not.
ov = gmsh.model.geo.twist([(2,50)], 0,0.15,0.25, -2*h,0,0, 1,0,0,
angle*pi/180., [10], [], true)6-element Array{Tuple{Int32,Int32},1}:
(2, 72)
(3, 3)
(2, 59)
(2, 63)
(2, 67)
(2, 71)gmsh.model.geo.synchronize()All the extrusion functions return a vector of extruded entities: the "top" of the extruded surface (in ov[0]), the newly created volume (in ov[1]) and the tags of the lateral surfaces (in ov[2], ov[3], ...).
We can then define a new physical volume (with tag 101) to group all the elementary volumes:
gmsh.model.addPhysicalGroup(3, [1, 2, ov[2][2]], 101)101gmsh.model.mesh.generate(3)
gmsh.write("t3.msh")Info : Meshing 1D...
Info : [ 0%] Meshing curve 1 (Line)
Info : [ 10%] Meshing curve 2 (Line)
Info : [ 10%] Meshing curve 3 (Line)
Info : [ 20%] Meshing curve 4 (Line)
Info : [ 20%] Meshing curve 8 (Extruded)
Info : [ 20%] Meshing curve 9 (Extruded)
Info : [ 30%] Meshing curve 10 (Extruded)
Info : [ 30%] Meshing curve 11 (Extruded)
Info : [ 30%] Meshing curve 13 (Extruded)
Info : [ 40%] Meshing curve 14 (Extruded)
Info : [ 40%] Meshing curve 18 (Extruded)
Info : [ 40%] Meshing curve 22 (Extruded)
Info : [ 50%] Meshing curve 30 (Extruded)
Info : [ 50%] Meshing curve 31 (Extruded)
Info : [ 50%] Meshing curve 32 (Extruded)
Info : [ 60%] Meshing curve 33 (Extruded)
Info : [ 60%] Meshing curve 35 (Extruded)
Info : [ 70%] Meshing curve 36 (Extruded)
Info : [ 70%] Meshing curve 40 (Extruded)
Info : [ 70%] Meshing curve 44 (Extruded)
Info : [ 80%] Meshing curve 52 (Extruded)
Info : [ 80%] Meshing curve 53 (Extruded)
Info : [ 80%] Meshing curve 54 (Extruded)
Info : [ 90%] Meshing curve 55 (Extruded)
Info : [ 90%] Meshing curve 57 (Extruded)
Info : [ 90%] Meshing curve 58 (Extruded)
Info : [100%] Meshing curve 62 (Extruded)
Info : [100%] Meshing curve 66 (Extruded)
Info : Done meshing 1D (Wall 0.000513707s, CPU 0.000507s)
Info : Meshing 2D...
Info : [ 0%] Meshing surface 1 (Plane, Frontal-Delaunay)
Info : [ 10%] Meshing surface 15 (Extruded)
Info : [ 20%] Meshing surface 19 (Extruded)
Info : [ 20%] Meshing surface 23 (Extruded)
Info : [ 30%] Meshing surface 27 (Extruded)
Info : [ 40%] Meshing surface 28 (Extruded)
Info : [ 40%] Meshing surface 37 (Extruded)
Info : [ 50%] Meshing surface 41 (Extruded)
Info : [ 50%] Meshing surface 45 (Extruded)
Info : [ 60%] Meshing surface 49 (Extruded)
Info : [ 70%] Meshing surface 50 (Extruded)
Info : [ 70%] Meshing surface 59 (Extruded)
Info : [ 80%] Meshing surface 63 (Extruded)
Info : [ 90%] Meshing surface 67 (Extruded)
Info : [ 90%] Meshing surface 71 (Extruded)
Info : [100%] Meshing surface 72 (Extruded)
Info : Done meshing 2D (Wall 0.0260809s, CPU 0.026069s)
Info : Meshing 3D...
Info : Meshing volume 1 (Extruded)
Info : Meshing volume 2 (Extruded)
Info : Meshing volume 3 (Extruded)
Info : Subdividing extruded mesh
Info : Swapping 391
Info : Swapping 51
Info : Swapping 0
Info : Remeshing surface 15
Info : Meshing surface 15 (Extruded)
Info : Remeshing surface 45
Info : Meshing surface 45 (Extruded)
Info : Remeshing surface 49
Info : Meshing surface 49 (Extruded)
Info : Remeshing surface 27
Info : Meshing surface 27 (Extruded)
Info : Remeshing surface 19
Info : Meshing surface 19 (Extruded)
Info : Remeshing surface 23
Info : Meshing surface 23 (Extruded)
Info : Remeshing surface 37
Info : Meshing surface 37 (Extruded)
Info : Remeshing surface 41
Info : Meshing surface 41 (Extruded)
Info : Done meshing 3D (Wall 0.180327s, CPU 0.180275s)
Info : Optimizing mesh...
Info : Done optimizing mesh (Wall 0.00117442s, CPU 0.001174s)
Info : 11302 nodes 51042 elements
Info : Writing 't3.msh'...
Info : Done writing 't3.msh'gmsh.finalize()This page was generated using Literate.jl.