Multi-entity models#
Multiple GMSH entities (and polysurfaces or prisms) can be provided to a model to create a single mesh.
from functools import partial
import gmsh
import shapely
from meshwell.cad import cad
from meshwell.gmsh_entity import GMSH_entity
from meshwell.mesh import mesh
from meshwell.polysurface import PolySurface
from meshwell.visualization import plot2D
polygon_hull = shapely.Polygon(
[[0, 0], [2, 0], [2, 2], [0, 2], [0, 0]],
)
line1 = shapely.LineString([[0.5, 0.5], [1.5, 1.5]])
polygon_hole1 = shapely.buffer(line1, 0.2)
line2 = shapely.LineString([[1.5, 0.5], [0.5, 1.5]])
polygon_hole2 = shapely.buffer(line2, 0.2)
polygon = polygon_hull - polygon_hole1 - polygon_hole2
s_curve = shapely.LineString([[-1, 0], [0, 0.5], [-1, 1], [0, 1.5], [-1, 2]])
s_shape = shapely.buffer(s_curve, 0.2)
poly2D = PolySurface(
polygons=polygon,
physical_name="meshwell_polygon",
mesh_order=1,
)
s = PolySurface(
polygons=s_shape,
physical_name="meshwell_s",
mesh_order=2,
)
gmsh_entity = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_disk, xc=2, yc=2, zc=0, rx=1, ry=1
),
physical_name="gmsh_disk",
mesh_order=3,
)
rectangle = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_rectangle, x=1.5, y=0, z=0, dx=1, dy=1
),
physical_name="gmsh_rectangle",
mesh_order=4,
)
entities_list = [poly2D, s, gmsh_entity, rectangle]
cad(
entities_list=entities_list,
output_file="complicated.xao",
)
output_mesh = mesh(
dim=2,
input_file="complicated.xao",
output_file="complicated.msh",
default_characteristic_length=0.5,
mesh_element_order=1, # set to 2 to generate a curved mesh with the disk
)
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Info : Cannot bind existing OpenCASCADE surface 1 to second tag 2
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Info : Cannot bind existing OpenCASCADE surface 1 to second tag 4
Info : Could not preserve tag of 2D object 4 (->1)
Info : Cannot bind existing OpenCASCADE surface 1 to second tag 5
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Info : Writing 'complicated.xao'...
Info : Done writing 'complicated.xao'
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Info : Done clearing all models and views
Info : Reading 'complicated.xao'...
Info : Done reading 'complicated.xao'
plot2D(output_mesh, wireframe=False)
plot2D(output_mesh, wireframe=False, physicals=["meshwell_polygon___gmsh_disk"])
mesh_order specifies which entity takes precedence if there is a conflict; lower numbers override higher numbers.
poly2D = PolySurface(
polygons=polygon,
physical_name="meshwell_polygon",
mesh_order=4,
)
s = PolySurface(
polygons=s_shape,
physical_name="meshwell_s",
mesh_order=3,
)
gmsh_entity = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_disk, xc=2, yc=2, zc=0, rx=1, ry=1
),
physical_name="gmsh_disk",
mesh_order=2,
)
rectangle = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_rectangle, x=1.5, y=0, z=0, dx=1, dy=1
),
physical_name="gmsh_rectangle",
mesh_order=1,
)
entities_list = [poly2D, s, gmsh_entity, rectangle]
cad(
entities_list=entities_list,
output_file="model.xao",
)
output_mesh = mesh(
dim=2,
input_file="model.xao",
output_file="model.msh",
default_characteristic_length=0.5,
mesh_element_order=1, # set to 2 to generate a curved mesh with the disk
)
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Info : Cannot bind existing OpenCASCADE surface 1 to second tag 2
Info : Could not preserve tag of 2D object 2 (->1)
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Info : Cannot bind existing OpenCASCADE surface 4 to second tag 5
Info : Could not preserve tag of 2D object 5 (->4)
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Info : Writing 'model.xao'...
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plot2D(output_mesh, wireframe=True)
By default, all CAD entities get meshed. By setting meshbool to False, a CAD entity can be inserted for the purposes of cutting out regions / tagging interfaces, without adding a mesh within a region.
poly2D = PolySurface(
polygons=polygon,
physical_name="meshwell_polygon",
mesh_order=4,
)
s = PolySurface(
polygons=s_shape,
physical_name="meshwell_s",
mesh_order=3,
mesh_bool=False, # Don't mesh this entity
)
gmsh_entity = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_disk, xc=2, yc=2, zc=0, rx=1, ry=1
),
physical_name="gmsh_disk",
mesh_order=2,
mesh_bool=False, # Don't mesh this entity
)
rectangle = GMSH_entity(
gmsh_partial_function=partial(
gmsh.model.occ.add_rectangle, x=1.5, y=0, z=0, dx=1, dy=1
),
physical_name="gmsh_rectangle",
mesh_order=1,
)
entities_list = [poly2D, s, gmsh_entity, rectangle]
cad(
entities_list=entities_list,
output_file="model.xao",
)
output_mesh = mesh(
dim=2,
input_file="model.xao",
output_file="model.msh",
default_characteristic_length=0.5,
mesh_element_order=1, # set to 2 to generate a curved mesh with the disk
)
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Info : Cannot bind existing OpenCASCADE surface 1 to second tag 2
Info : Could not preserve tag of 2D object 2 (->1)
Info : Cannot bind existing OpenCASCADE surface 1 to second tag 3
Info : Could not preserve tag of 2D object 3 (->1)
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Info : Cannot bind existing OpenCASCADE surface 4 to second tag 5
Info : Could not preserve tag of 2D object 5 (->4)
Info : Cannot bind existing OpenCASCADE surface 4 to second tag 6
Info : Could not preserve tag of 2D object 6 (->4)
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Info : Cannot bind existing OpenCASCADE surface 7 to second tag 8
Info : Could not preserve tag of 2D object 8 (->7)
Info : Cannot bind existing OpenCASCADE surface 7 to second tag 9
Info : Could not preserve tag of 2D object 9 (->7)
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Info : Writing 'model.xao'...
Info : Done writing 'model.xao'
Info : Clearing all models and views...
Info : Done clearing all models and views
Info : Reading 'model.xao'...
Info : Done reading 'model.xao'
plot2D(output_mesh, wireframe=True)
