Boundary Meshes (`data.boundaries`)¶

The finbound / legacy boundaries defined under MPIEMSES’s &ptcond are exposed as Python objects via data.boundaries. Each boundary produces a MeshSurface3D that you can overlay onto a 3D field plot or style individually.

Note: mesh() returns SI units by default. data.boundaries[0].mesh() gives you vertex coordinates in metres. Pass mesh(use_si=False) explicitly when you want grid-unit meshes (for example when feeding the mesh into a grid-space computation). When overlaying via plot_surfaces(), make sure the field axis units and the mesh units agree — mismatched units show up as boundaries that look slightly offset from the field.

Access¶

# The whole collection
data.boundaries                 # BoundaryCollection (iterable, indexable)
len(data.boundaries)
data.boundaries.types           # list of boundary_types strings
data.boundaries.skipped         # [(index, type_name, reason), ...]

# An individual boundary
data.boundaries[0]              # subclass (SphereBoundary, CylinderBoundary, ...)
data.boundaries[0].btype        # e.g. "sphere", "cylinderz"
data.boundaries[0].mesh()       # → MeshSurface3D (SI units by default)
data.boundaries[0].mesh(use_si=False)  # keep grid units

Overlay on a 3D field plot¶

Pass data.boundaries straight to Data3d.plot_surfaces to draw the geometries on top of isosurfaces or slices.

import matplotlib.pyplot as plt

fig = plt.figure(figsize=(8, 6))
ax = fig.add_subplot(111, projection="3d")

data.phisp[-1].plot_surfaces(
    ax=ax,
    surfaces=data.boundaries,         # auto-wrapped into RenderItems
)
plt.show()

Composite mesh¶

All boundaries can be fused into a single mesh for further processing:

composite = data.boundaries.mesh()    # → CompositeMeshSurface
V, F = composite.mesh()               # raw (vertices, faces) arrays

Composition and per-boundary styling¶

# Boundary + Boundary → BoundaryCollection
combined = data.boundaries[0] + data.boundaries[1]

# Different style per boundary
data.phisp[-1].plot_surfaces(
    ax=ax,
    surfaces=data.boundaries.render(
        per={
            0: dict(style="solid", solid_color="0.7"),
            1: dict(alpha=0.5),
        },
    ),
)

Overriding mesh parameters¶

You can pass keyword arguments through mesh() to adjust resolution or geometry without modifying the simulation parameters:

# Higher angular resolution on a specific boundary
data.boundaries[0].mesh(ntheta=64)

# Per-boundary overrides via the collection
data.boundaries.mesh(per={0: dict(ntheta=64)})

Supported boundary types¶

Both boundary_type = "complex" with boundary_types(i) and the legacy single-body modes are supported.

Category	Type names
Closed solids	`sphere`, `cuboid`
Cylinders	`cylinderx/y/z`, `open-cylinderx/y/z`
Flat panels	`rectangle`, `circlex/y/z`, `diskx/y/z`, `plane-with-circlex/y/z`
Legacy single-body	`flat-surface`, `rectangle-hole`, `cylinder-hole`

See MPIEMSES3D Parameters.md for the full parameter specification.

Unregistered types are recorded in data.boundaries.skipped as (index, type_name, reason) tuples rather than raising an error. You can inspect this list to check whether any boundaries were silently ignored.

Available mesh surface classes¶

Each boundary type maps to one of these MeshSurface3D subclasses (importable from emout.plot.surface_cut):

Class	Used by
`SphereMeshSurface`	`sphere`
`BoxMeshSurface`	`cuboid`
`RectangleMeshSurface`	`rectangle`
`CircleMeshSurface`	`circlex/y/z`
`CylinderMeshSurface`	`cylinderx/y/z`, `open-cylinderx/y/z`
`DiskMeshSurface`	`diskx/y/z`
`PlaneWithCircleMeshSurface`	`plane-with-circlex/y/z`
`HollowCylinderMeshSurface`	`cylinder-hole`
`CompositeMeshSurface`	collection-level `mesh()` output

These classes can also be instantiated directly for standalone mesh construction without going through data.boundaries.

Boundary Meshes (data.boundaries)¶