Capsule Particles Model Reference

The Capsule Particles model allows you to use capsule-shaped particles of specified size and proportion rather than polyhedral particles or particles composed of combinations of spheres.

Using capsule particles to model the shape of a cylinder with hemispherical caps can be simpler, computationally less expensive, and more accurate than using a polyhedral approximation or a combinations of spheres, depending on the individual case.

Provided By [phase] > Models > Particle Shape
Example Node Path Continua > Physics 1 > Models > Lagrangian Multiphase > Lagrangian Phases > [phase] > Models > Capsule Particles
Requires In [physics continuum] > Models:
  • Optional Models: Discrete Element Method (DEM)

In [phase] > Models:

  • Particle Type: DEM Particles
Properties
Moment of Inertia Scaling

Provides a scaling factor for each axis of the moment of inertia of the particle. This can be used to simulate effects such as uneven distribution of mass within the particle, or the dynamical response of a non-spherical particle. The scaling factor has an allowed range on each axis of 1E-2 to 1E5. The default value is [1.0, 1.0, 1.0].

Activates Region Inputs Physics Conditions > Energy Source Option

Physics Values > Axis and Motion Specification

Injector Inputs See Capsule Particles Injector Inputs.
Field Functions
  • Cylinder Height
  • Cylinder Radius
  • Particle Projected Area
  • Particle Projected Length

See Discrete Element Method Field Functions Reference.

Capsule Particles Injector Inputs

The Capsule Particles model activates the following injector conditions:
Orientation Specification
Sets the initial orientation of the particle as it is injected.
The Capsule Particles model activates the following injector values:
Cylinder Height
Sets the heights of the cylindrical sections using a selection of methods.
Cylinder Height/Radius Ratio
Sets the ratio of height to radius of the cylindrical sections using a selection of methods.
Cylinder Radius
Sets the radii of the cylindrical sections using a selection of methods.
Particle Orientation
Sets the initial orientation of the particle as it is injected.

The Capsule Particles model is incompatible with the Random Injector using the Maximum Packing option.

Contact Force Modeling for Capsule Particles

Use Linear Spring to model contact force, and set the Spring Stiffness methods to Constant. The default value for stiffness, 100000.0 N/m, works for most situations. However, for capsules with very small aspect ratios, use higher values to avoid large overlap between capsules, especially capsules penetrating the boundary.

Compatibility with Other Models

The following models are incompatible with the Capsule Particles model:

  • Artificial Viscosity
  • Hertz Mindlin
  • Linear Cohesion
  • Linear Spring, with either Normal Spring Stiffness Method or Tangential Spring Stiffness Method set to Particle Material Based.
  • Parallel Bond
  • Rolling Resistance, using the Displacement Damping or Constant Torque method
  • Walton Braun