Materials

Atom Sand

Dry granular material (sand, soil, gravel) for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Friction Angle	Internal friction angle (degrees): the angle of repose a pile settles at	33
Cohesion (Pa)	Tensile strength between grains: 0 dry sand, ~1 kPa damp sand, a few kPa soil	0
Friction Hardening	Friction starts 10 degrees lower and rises to the friction angle as the material is worked (soil, compacting sand)	False
Young’s Modulus (Pa)	Grain-skeleton stiffness. Higher is closer to real sand and costs substeps	200000
Poisson Ratio	How strongly the grains resist volume change when squeezed. 0.45 is nearly incompressible	0.3
Density (kg/m³)	Bulk density in kg/m³ (dry sand ~1600, wet ~1900)	1600

Rubber or jelly that deforms and springs back, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Young’s Modulus (Pa)	Stiffness: gelatin 5-50 kPa, rubber ~1 MPa. Higher costs substeps	15000
Poisson Ratio	Volume preservation: 0.49 nearly incompressible	0.35
Damping (Pa·s)	Kelvin-Voigt viscosity of the deformation: how fast a wobble dies out (rigid motion is not damped). 0 rings until contacts stop it	40
Critical Stretch	Stretch at which the material tears (0.5 = 50% elongation); 0 never tears	0
Density (kg/m³)	Mass per volume in kg/m³ (gelatin ~1050, rubber ~1100)	1050

Snow that packs, compresses and breaks apart, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Young’s Modulus (Pa)	Stiffness of the snow. Higher is more rigid and costs substeps	140000
Poisson Ratio	How strongly the snow resists volume change when squeezed. 0.45 is nearly incompressible	0.2
Critical Compression	Compression past which snow packs down for good. Larger values pack more	0.025
Critical Stretch	Stretch past which snow breaks. Smaller values are more brittle and chunkier	0.0075
Hardening	How much packing stiffens the snow. 0 means no hardening	10
Heat Conductivity	How fast heat reaches the snow (it melts into water past the melting temperature); thermal diffusivity in 1e-4 m^2/s	12
Density (kg/m³)	Mass per volume in kg/m³ (fresh snow ~100, packed snow ~400)	400

Mud or clay that holds its shape until pushed hard enough, then flows, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Kind	Whether the material behaves as flowing mud or as clay that stiffens when kneaded	MUD
Yield Stress (Pa)	Shear stress below which it holds its shape (mud 50-500, clay 1-10 kPa)	200
Consistency (Pa·sⁿ)	Thickness of the flowing material. Higher flows slower once it yields	20
Flow Index (n)	< 1 shear-thinning, 1 Bingham plastic, > 1 shear-thickening	0.6
Young’s Modulus (Pa)	Elastic stiffness below the yield stress	50000
Poisson Ratio	How strongly the material resists volume change when squeezed. 0.45 is nearly incompressible	0.3
Density (kg/m³)	Mass per volume in kg/m³ (wet mud ~1800)	1800

Viscous fluid such as slime, honey or oil, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Viscosity (Pa·s)	Dynamic viscosity in Pa s: water 0.001, oil ~0.1, honey ~10, slime a few	0.001
Sound Speed (m/s)	Speed of sound in m/s: lower is more compressible, higher is stiffer and costs substeps	12
Surface Tension (N/m)	Surface tension coefficient in N/m that rounds droplets and holds the fluid together; 0 is off	0
Density (kg/m³)	Mass per volume in kg/m³ (water 1000, honey ~1400)	1000

Hot lava that flows thinly, then cools and crusts over, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Hot Viscosity (Pa·s)	Viscosity of the molten lava (basalt 10-100 Pa s)	50
Cold Viscosity (Pa·s)	Viscosity once cooled (the crust’s stiffness carries the rest; high values cost substeps)	300
Crust Modulus (Pa)	Young’s modulus of the cooled crust	200000
Sound Speed (m/s)	Speed of sound in m/s. Lower is more compressible, higher is stiffer and costs substeps	12
Cooling Rate (/s)	How fast the lava loses heat, as a fraction of its temperature per second. 0 never cools	0.25
Heat Conduction	Thermal diffusivity in 1e-4 m^2/s	12
Surface Tension	Surface tension in N/m that pulls the lava into rounded blobs. 0 turns it off	0.2
Density (kg/m³)	Mass per volume in kg/m³ (molten basalt ~2600)	2600

Metal that bends permanently and can tear, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Young’s Modulus (Pa)	Stiffness, scaled far below real steel (2e11 Pa) to keep the substep count practical	8e+06
Poisson Ratio	How strongly the metal resists volume change when squeezed. 0.49 is nearly incompressible	0.3
Yield Stress (Pa)	Von Mises stress at which the metal starts to flow plastically (bends and stays bent)	40000
Hardening (Pa)	Yield stress gained per unit plastic strain (work hardening)	200000
Failure Strain	Plastic strain at which the metal tears (0 never)	0.6
Density (kg/m³)	Mass per volume in kg/m³ (steel ~7800)	7800

Brittle material that cracks under tension and crushes into rubble, for the Atom solver.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Material preset (SI values); Custom keeps your edits
Young’s Modulus (Pa)	Stiffness, scaled far below real concrete (3e10 Pa) to keep the substep count practical	3e+06
Poisson Ratio	How strongly the concrete resists volume change when squeezed. 0.49 is nearly incompressible	0.2
Tensile Strength (Pa)	Tension at which a crack starts	20000
Fracture Energy (J/m²)	Energy a crack absorbs per unit area while it opens: low snaps (glass), high crumbles	5
Density (kg/m³)	Mass per volume in kg/m³ (concrete ~2400)	2400

Liquid properties for the Hydro solver: density, viscosity and surface tension.

Outputs: Material: Physical material of the particles or pieces. Connect one mater

Setting	What it does	Default
Preset	Real-world liquid values at about 20 °C. Picking one writes them in Physical units; Custom keeps your values
Units	Physical: real units, the same look at any domain size or substep count. Solver: the raw solver values	PHYSICAL
Viscosity (mPa·s)	Dynamic viscosity in mPa·s (centipoise): water 1, olive oil 80, honey 2,000 to 10,000	1
Surface Tension (mN/m)	Surface tension in mN/m: water 72.8, oils about 32. Sets how strongly drops round and cling, relative to water	72.8
Viscosity (Smoothed)	Solver units: the share of the neighbours’ velocity a particle blends in each substep. Thicker as it rises, and with more substeps	0.01
Implicit Viscosity	Solver units: extra stable viscosity for thick liquids, in domain lengths² per second. 0 uses the smoothed blend alone	0
Cohesion	Solver units: the cohesion strength that holds the liquid together and rounds drops (0.05 is water)	0.05
Density (kg/m³)	Density at rest in kg/m³: water 998, olive oil 910, honey 1420. The lighter liquid floats	998