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Geometry & Meshing

PalaceToolkit uses Gmsh with its OpenCASCADE kernel to create parametric 3D finite-element meshes entirely from Python scripts.

The Entity abstraction

Every geometric region — conductors, dielectrics, air boxes, ports — is represented as an Entity:

from palacetoolkit.mesh import Entity, run_meshing_pipeline

conductor = Entity(name="conductor", dim=3, mesh_order=0, tags=[1])
dielectric = Entity(name="dielectric", dim=3, mesh_order=1, tags=[2])
air = Entity(name="air", dim=3, mesh_order=2, tags=[3])
Parameter Description
name Becomes the physical group label that Palace references.
dim Geometric dimension (3 = volume, 2 = surface, …).
mesh_order Priority for the boolean pipeline (lower = higher priority).
tags Gmsh geometry tags returned by gmsh.model.occ.* calls.

Boolean pipeline

After defining entities, call run_meshing_pipeline to perform automatic priority-based cuts and fragmentation:

run_meshing_pipeline([conductor, dielectric, air])

The pipeline:

  1. Groups entities by dimension (3 → 0).
  2. Sorts within each dimension by mesh_order (ascending = higher priority).
  3. Cuts each entity against all previously processed entities in the same dimension (removeObject=True, removeTool=False).
  4. Fragments lower-dimensional entities against higher-dimensional ones so that boundary surfaces are shared.
  5. Assigns physical groups — volumes get their entity name; surfaces at material interfaces are auto-labelled (e.g. "conductor__dielectric").

Tip

The mesh_order controls which material wins at overlapping regions. Think of it as a z-index: small number = highest priority = never cut.

Mesh generation

After the pipeline runs, generate the mesh and write it to disk:

import gmsh

gmsh.model.mesh.generate(3)
gmsh.write("my_model.msh")
gmsh.finalize()

Mesh topology verification

Before running Palace, verify the mesh is valid:

from palacetoolkit.verify_topology import analyse_mesh

analyse_mesh("my_model.msh")

This checks that:

  • Every boundary element maps to an existing volume face (totality).
  • No two boundary elements map to the same face (injectivity).

Mesh visualisation

from palacetoolkit.viz import view_mesh

view_mesh("my_model.msh")

For static HTML exports (used in the docs site):

from IPython.display import IFrame

from palacetoolkit.viz import render_mesh

render_mesh(mesh, Path("img") / "my_model.htm", title="My Model")
IFrame(src="img/my_model.htm", width="100%", height=500)