pipemesh 0.1.3

A package for making pipe network meshes.

pipemesh

These tools use the GMSH-SDK (or GMSH API), available here.

The documentation for pipemesh can be found here.

Installation

python3 -m pip install --user pipemesh

Once completed, navigate to site-packages/pipemesh. Place the files libgmsh.so, libgmsh.so.4.3 and libgmsh.so.4.3.0, which can be downloaded from the GMSH website (link above).

pieces.py

Contains classes (and some useful functions for said classes) which represent cylindrical GMSH objects. The classes store information of the object, such as the centre and direction of its faces, as well as functions to update the information when transformations are applied to them. This makes the information a little easier to access than using just the GMSH API. To use these individually start your file with:

from pipemesh import pieces
model = gmsh.model
mesh = model.mesh
gmsh.initialize()
gmsh.option.setNumber("Mesh.CharacteristicLengthMax", 0.1)  # max mesh length
model.add("Example")  # optional, add a model name.

The available pieces to put in are:

• Cylinder

piece = pieces.Cylinder(1, 0.5, [1,0,0], 0.1)
# Length, radius, direction, mesh size

• Cylinder with changing radius

piece = pieces.ChangeRadius(2, 1.8, 0.3, 0.2, [1 ,0, 0], 0.1)
# length, change length, start radius, end radius, direction, mesh size

• Smooth bends

piece = pieces.Curve(0.5, [1,0,-1], [0,1,0], 1, 0.2)
# radius of cylinder, in direction, out direction, bend radius, mesh size

• Mitered bends

piece = pieces.Mitered(0.5, [0, 1, 0], [1, 0, 0], 0.2)
# radius of cylinder, in direction, out direction, mesh size

• T Junctions

piece = pieces.TJunction(0.5, [1, 0, 0], [1, 1, -1], 0.1)
# radius, direction, t direction, mesh size

The mesh can be created and saved using:

mesh.generate(3)
gmsh.option.setNumber("Mesh.Binary", 1)  # 1 for binary, 0 for ASCII
gmsh.write(filename.msh)  # .msh2 for legacy format

To view the mesh in the GMSH GUI, call

gmsh.fltk.run()

To finish, and end use of gmsh, call

gmsh.finalize()

As of yet, just using the pieces on their own is limited, as they do not have translate, or rotate functions, but if desired, the user can look into the GMSH-SDK and develop some, or use pipes (below) to generate pipe meshes.

pipes.py

Using the pieces above and the Network class, pipes and pipe networks can be easily built. A Network is started with:

from pipemesh import pipes
network = pipes.Network(1, 0.3, [1,0,0], 0.1)

Then added to using one of the following commands:

network.add_cylinder(1, 0.1, out_number=1)
network.add_t_junction([-1,-1,0], 0.05)
network.add_curve([0,1,0], 0.5, 0.05)
network.add_mitered([0, 1, 0], 0.05, out_number=2)

Where out_number specifies which outlet of the pipe the piece will be added to. For more information on each function, the documentation is currently only within the files.

Examples:

• Chicane with mitered bends:

network = pipes.Network(1, 0.3, [1,0,0], 0.1)
network.add_cylinder(1, 0.1)
network.add_mitered([0,1,0], 0.1)
network.add_cylinder(1, 0.1)
network.add_mitered([1,0,0], 0.1)
network.add_cylinder(1, 0.1)

• Pipe with two junctions:

network.add_t_junction([-1,1,0], 0.05)
network.add_t_junction([-1,-1,0], 0.05)
network.add_cylinder(1, 0.1, out_number=2)
network.add_curve([-1,0,0], 0.5, 0.05, out_number=3)
network.add_cylinder(1.5, 0.1, out_number=3)

Once the network is complete, you can fuse the objects together and create physical surfaces and volumes, and set the local mesh sizes. Information can be obtained and written to file. This is all done with one call.

network.generate(filename="example", binary=False, write_info=False, mesh_format="msh2", write_xml=False run_gui=False)

Which will write the file "example.msh", as a msh2 binary file.

Requirements for pipes.py:

• libgmsh.so, libgmsh.so.4.3, libgmsh.so.4.3.0 from the GMSH SDK.
• NumPy, SciPy