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name: mesh-and-geometry description: "Use PhysicsNeMo-Mesh for Mesh/DomainMesh creation, validation, geometry/calculus, queries, repair/remesh, I/O, and visualization." metadata: disco-role: operating disable-model-invocation: true license: Apache 2.0

PhysicsNeMo mesh-and-geometry

Use this sub-skill when the task is about PhysicsNeMo-Mesh objects or mesh preprocessing rather than choosing a neural model or building a data reader.

Trigger phrases

• Mesh, DomainMesh, simplicial mesh, triangle mesh, tetrahedral mesh, point cloud, curve mesh.
• Mesh creation, field attachment, point_data, cell_data, global_data, TensorDict field ranks.
• Mesh validation, quality metrics, manifold/watertight checks, duplicate vertices, degenerate or inverted cells.
• Geometry or calculus: centroids, areas/volumes, normals, curvature, gradient, divergence, curl, Laplace-Beltrami.
• Neighbors, adjacency, BVH, spatial query, barycentric sampling/interpolation.
• Mesh repair, cleaning, subdivision, remeshing, transformations/deformation.
• PyVista/VTK conversion, Zarr/native mesh serialization, visualization caveats.

Fast route

1. Confirm the representation. PhysicsNeMo-Mesh accepts pure simplicial complexes: 0-simplices/points, 1-simplices/edges, 2-simplices/triangles, 3-simplices/tetrahedra, or higher-dimensional simplices. Do not treat arbitrary VTK polygons/polyhedra as directly supported until they are triangulated/tetrahedralized or converted through an explicit helper.
2. Choose object type. Use Mesh for one geometry and DomainMesh for an interior mesh plus named boundary meshes.
3. Import from the right surface. Root physicsnemo.mesh exports only the core object model and field-rank helpers. Validation, I/O, sampling, repair, remeshing, spatial, and calculus functions live in submodules.
4. Validate before expensive work. Check tensor shape/dtype/device, out-of-bounds indices, degeneracy, duplicate vertices, and optional manifoldness/inversion. Then compute quality metrics if mesh health matters.
5. Run operations on the mesh device. mesh.to("cuda") moves geometry and attached data together; PyVista/VTK visualization and conversion are CPU/external-library workflows.
6. Use references for details. Recipes: references/mesh-workflows.md. API/import map: references/api-reference.md. Failure modes: references/troubleshooting.md.

Minimal import pattern

from physicsnemo.mesh import DomainMesh, Mesh
from physicsnemo.mesh.validation import compute_quality_metrics, validate

# Compatibility alias exists in the validation submodule, not the mesh root:
from physicsnemo.mesh.validation import validate_mesh  # pending-deprecation alias

Never write from physicsnemo.mesh import validate_mesh; it is not a root export.

Validation checklist

• points: floating tensor with shape (n_points, n_spatial_dims).
• cells: integer tensor with shape (n_cells, n_manifold_dims + 1), same device as points; omit it or pass None for a point cloud.
• n_manifold_dims <= n_spatial_dims; triangles in 3D are valid, tetrahedra in 2D are not.
• Cell indices are in [0, n_points) and one cell should not repeat a vertex unless intentionally testing degeneracy.
• point_data leaves start with n_points; cell_data leaves start with n_cells; global_data has no leading mesh batch dimension.
• For semantic rank schemas, use root field helpers such as ranks_from_tensordict() and validate_data_contains_ranks().
• For DomainMesh, every boundary value must be a Mesh and share the interior spatial dimension; use dm.validate() plus dm.is_boundary_watertight() when boundary closure matters.

Sibling routes

• Model-family choice for MeshGraphNet, Transolver, DoMINO, FIGConvNet, or graph/geometry models: route to sibling sub-skill model-selection.
• Mesh file readers inside a training data pipeline, including MeshReader or DomainMeshReader: route to sibling sub-skill datapipes.
• Multi-GPU/domain-parallel training after mesh preprocessing: route to sibling sub-skill distributed-and-domain-parallel.
• Active-learning loops or ONNX export after mesh-based inference: route to sibling sub-skill active-learning-and-deployment.

Bundled smoke

Run a tiny local check without downloads:

python sub-skills/mesh-and-geometry/scripts/mesh_smoke.py
python sub-skills/mesh-and-geometry/scripts/mesh_smoke.py --cuda

The --cuda path only moves a three-point triangle mesh to CUDA when CUDA is available.