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Generate flat elements


Double nodes on groups boundaries


Double nodes on shared faces between groups of volumes and create flat elements on demand.
The list of groups must describe a partition of the mesh volumes. The nodes of the internal faces at the boundaries of the groups are doubled. Optionally, the internal faces are replaced by flat elements.
Triangles are transformed into prisms, and quadrangles into hexahedrons.
The flat elements are stored in groups of volumes.



This example represents an iron cable (a thin cylinder) in a concrete bloc (a big cylinder). The big cylinder is defined by two geometric volumes.

import geompy
import smesh
import SMESH
# geometry
O = geompy.MakeVertex(0, 0, 0)
OX = geompy.MakeVectorDXDYDZ(1, 0, 0)
OY = geompy.MakeVectorDXDYDZ(0, 1, 0)
OZ = geompy.MakeVectorDXDYDZ(0, 0, 1)
Vertex_1 = geompy.MakeVertex(50, 0, 0)
Cylinder_1 = geompy.MakeCylinder(O, OX, 10, 500)
Cylinder_2 = geompy.MakeCylinder(Vertex_1, OX, 100, 400)
Vertex_2 = geompy.MakeVertex(-200, -200, -200)
Vertex_3 = geompy.MakeVertex(250, 200, 200)
Box_1 = geompy.MakeBoxTwoPnt(Vertex_2, Vertex_3)
Fuse_1 = geompy.MakeFuse(Cylinder_1, Cylinder_2)
Partition_1 = geompy.MakePartition([Fuse_1], [Cylinder_1, Box_1], [], [], geompy.ShapeType["SOLID"], 0, [], 0)
[Solid_1,Solid_2] = geompy.GetShapesOnShape(Cylinder_1, Partition_1, geompy.ShapeType["SOLID"], geompy.GEOM.ST_IN)
[Solid_3,Solid_4] = geompy.GetShapesOnShape(Cylinder_2, Partition_1, geompy.ShapeType["SOLID"], geompy.GEOM.ST_IN)
Vertex_4 = geompy.MakeVertex(450, 0, 0)
Vertex_5 = geompy.MakeVertex(500, 0, 0)
Vertex_6 = geompy.MakeVertex(550, 0, 0)
vec1 = geompy.MakeVector(Vertex_4, Vertex_5)
vec2 = geompy.MakeVector(Vertex_5, Vertex_6)
[Face_1] = geompy.GetShapesOnPlane(Partition_1, geompy.ShapeType["FACE"], vec1, geompy.GEOM.ST_ON)
[Face_2] = geompy.GetShapesOnPlane(Partition_1, geompy.ShapeType["FACE"], vec2, geompy.GEOM.ST_ON)
# meshing (we have linear tetrahedrons here, but other elements are OK)
Mesh_1 = smesh.Mesh(Partition_1)
Regular_1D = Mesh_1.Segment()
Nb_Segments_1 = Regular_1D.NumberOfSegments(15)
MEFISTO_2D = Mesh_1.Triangle(algo=smesh.MEFISTO)
Length_From_Edges_2D = MEFISTO_2D.LengthFromEdges()
ALGO3D = Mesh_1.Tetrahedron()
isDone = Mesh_1.Compute()
# relevant groups of volumes and faces
Solid_1_1 = Mesh_1.GroupOnGeom(Solid_1,'Solid_1',SMESH.VOLUME)
Solid_2_1 = Mesh_1.GroupOnGeom(Solid_2,'Solid_2',SMESH.VOLUME)
Solid_3_1 = Mesh_1.GroupOnGeom(Solid_3,'Solid_3',SMESH.VOLUME)
Solid_4_1 = Mesh_1.GroupOnGeom(Solid_4,'Solid_4',SMESH.VOLUME)
Face_1_1 = Mesh_1.GroupOnGeom(Face_1,'Face_1',SMESH.FACE)
Face_2_1 = Mesh_1.GroupOnGeom(Face_2,'Face_2',SMESH.FACE)


Here, the 4 groups of volumes [Solid_1_1, Solid_2_1, Solid_3_1, Solid_4_1] constitute a partition of the mesh. The flat elements on group boundaries and on faces are built with the following code.
If the last argument (Boolean) in DoubleNodesOnGroupBoundaries is set to 1, the flat elements are built, otherwise, there is only a duplication of the nodes.

Mesh_1.DoubleNodesOnGroupBoundaries([Solid_1_1, Solid_2_1, Solid_3_1, Solid_4_1], 1)
Mesh_1.CreateFlatElementsOnFacesGroups([Face_1_1, Face_2_1])


To observe flat element groups, save the resulting mesh on a MED file and reload it.

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