nemoblock

Project description

nemoblock provides utilities to generate blockMeshDicts for structured mesh generation in OpenFOAM. It manages the numbering of the points, the orientation of the surfaces and the connections between the blocks. In this way it helps the user to focus on the most important point: generating high quality meshes.

The project is developed and maintained by the Model experiments group at the Leibniz Institute for Crystal Growth (IKZ).

Referencing

If you use this code in your research, please cite our article:

TODO

Prerequisites

nemoblock requires Python >= 3.7. The following dependencies are installed automatically: matplotlib, numpy, scipy.

If you encounter any problems with these packages try:

pip install --upgrade matplotlib
pip install --upgrade numpy
pip install --upgrade scipy

Installation

The latest release can be installed using pip:

pip install nemoblock

Usage

nemoblock follows the naming conventions in the OpenFOAM user guide:

To initialize nemoblock you have to create a mesh object:

import nemoblock as nb
mesh = nb.Mesh()

You can then create a block object with the mesh and points p0 to p7 :

b1 = b1 = nb.Block(
    mesh,
    [0, 0, 0],
    [1, 0, 0],
    [1, 1, 0],
    [0, 1, 0],
    [0, 0, 1],
    [1, 0, 1],
    [1, 1, 1],
    [0, 1, 1],
)

Then, you can set the number of cells in x1, x2 and x3 direction and modify the grading:

b1.set_number_of_cells(10, 10, 10)
b1.grading = "simpleGrading (1 1 1)"  # this is the default

When all the points are defined you have to "create" the block:

b1.create()

This creates the edges e0 to e11 that can then be modified, e.g. to form an arc:

b1.e0.type = "arc"
b1.e0.points.append([0.5, 0.3, 0])

If you add additional blocks you have to set the relations:

b2 = nb.Block(mesh)  # raw block
b2.set_connection(b1, "bottom")  # on top of b1
# define missing points
b2.p4 = [0, 0, 2]
b2.p5 = [1, 0, 2]
b2.p6 = [1, 1, 2]
b2.p7 = [0, 1, 2]
# set number of cells
b2.cells_x3 = 5  # the others were derived from b1
b2.create()

However, this does only work if the coordinate systems of the blocks have the same orientation. In more complex cases you can use:

b2.face_top = b1.face_bottom
# define missing points
...
# set number of cells
b2.set_number_of_cells(10, 10, 5) 
# In this case you have to provide the number of cells for all directions.
# Make sure that this is conforming with b1!

Only use this if your mesh topology requires it, because it is prone to errors.

Eventually, you can create a patch, e.g. an inlet and export your blockMeshDict:

inlet = nb.Patch(mesh, "inlet inlet")
inlet.add_face(b1.face_bottom)

mesh.write()

The resulting mesh looks like this:

Examples

Examples, e.g. with grading for boundary layers or much more complex meshes generated using pre-defined cylinders and rings, can be found in the examples directory. This includes the setup for a mesh with the following structure:

License

nemoblock is published under the GPLv3 license.

Acknowledgements

This project has received funding from the European Research Council (ERC) under the European Union's Horizon 2020 research and innovation programme (grant agreement No 851768).

Contribution

Any help to improve this package is very welcome!