dem_atom

Per-atom DEM data and material property management for MDDEM.

DemAtom

DemAtom stores per-atom DEM-specific fields as flat arrays:

• radius: Vec<f64> — particle radius
• density: Vec<f64> — particle density

Implements the AtomData trait (via #[derive(AtomData)]) for automatic MPI pack/unpack, bin-sort reordering, and restart serialization.

MaterialTable

MaterialTable manages named material types with per-material and per-pair precomputed properties:

• Per-material: youngs_mod, poisson_ratio, restitution, friction
• Per-pair: beta_ij (damping coefficient from restitution), friction_ij (Coulomb friction coefficient)

Pair properties use geometric-mean mixing (LAMMPS convention): e_ij = sqrt(e_i * e_j), mu_ij = sqrt(mu_i * mu_j).

Configuration

[[dem.materials]]
name = "glass"
youngs_mod = 8.7e9
poisson_ratio = 0.3
restitution = 0.95
friction = 0.4

[[dem.materials]]
name = "steel"
youngs_mod = 200e9
poisson_ratio = 0.28
restitution = 0.8
friction = 0.3

Usage

DemAtomPlugin is included in GranularDefaultPlugins. It registers DemAtom with the AtomDataRegistry and builds MaterialTable from config at plugin build time.

Part of the MDDEM workspace.