Discrete Element Method Field Functions Reference

These objects all have the same base properties.

Abrasive Wear Rate

The rate at which material is being eroded from a boundary by abrasion. To access this field function, select the Abrasive Wear model.

Bond Damage

The damage to a bond, on a scale from 0 (undamaged) to 1 (broken). See $k_r$ in Eqn. (3298). To access this field function, select the Simple Failure or Constant Rate Damage model.

Bond Shear Strength

The shear strength of the bond, specified for each bonded contact, based on values assigned in the Simple Failure model. See ${\sigma }_{\text{max}}$ in Eqn. (3293).

Bond State

Indicates whether any given particle contact is bonded (value 1) or not (value 0). To access this field function, select the Bonded Particles or Parallel Bonds model.

Bond Tensile Strength

The tensile strength of the bond, specified for each bonded contact, based on values assigned in the Simple Failure or Constant Rate Damage models. See ${\delta }_{\text{max}}$ in Eqn. (3292).

Bonded Component Size

The number of spheres in the bonded particle cluster to which a given particle belongs. Compare with the Particle Connected Component Size field function.

Bonded Components

The labels (integers) of bonded particle clusters. These clusters are groups of particles that form a single connected network through particle-particle bonds. Compare with the Particle Connected Components field function.

Compression Force

The sum of contacts over the parcel, $K_n{d}_n$ in Eqn. (3251) or $K_n{\delta }_n$ in Eqn. (3268).

Contact Centroid

The coordinates of the contact point between colliding particles.

Contact Contact Mass 0|1

The mass of one of the individual component particles (0 or 1) making contact when composite particles or particle clumps collide.

Contact Contact Radius 0|1

The radius of one of the individual component particles (0 or 1) making contact when composite particles or particle clumps collide.

Contact Damping Force

The non-elastic component of the contact force between two particles, that is, the contact force minus the elastic component. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Elastic Force

The elastic component of the contact force between two particles, that is, the contact force minus the damping component. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Force

The total contact force between two particles, that is, the damping force plus the elastic force. See ${\mathbf{\text{F}}}_c$ in Eqn. (2959).

Contact Normal

A unit length vector perpendicular (orthogonal) to the contact plane. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Normal Overlap

The contact normal vector that is multiplied by the overlap, giving the direction and magnitude of the particle overlap, normal to the contact plane. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Overlap

The amount of overlap between two particles or a particle and wall boundary upon contact. This overlap occurs as the particles are modeled using soft-particle formulation, which permits a small overlap. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Physics Radius 0|1

The radius of one of the two particles (0 or 1) in a collision.

Contact Poisson Ratio 0|1

The Poisson ratio for one of the two particles (0 or 1) in a collision.

Contact Relative Velocity

The relative velocity between two contacting particles. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Surface Velocity 0|1

The surface velocity vector ${\mathbf{v}}_s$ at the point of contact for one of the two particles (0 or 1) in a collision. ${\mathbf{v}}_s={\mathbf{v}}_p+{\mathbf{\omega }}_p\times ({\mathbf{x}}_c-{\mathbf{x}}_p)$ , where ${\mathbf{v}}_p$ and ${\mathbf{\omega }}_p$ are the linear and angular velocities of the particle, ${\mathbf{x}}_c$ is the position of the contact, and ${\mathbf{x}}_p$ is the position of the particle. To access this field function, select the User-Defined Contact Force model.

Contact Tangential Overlap

The magnitude and direction of the particle overlap, tangential to the contact. To access this field function, select the DEM Particles, DEM Phase Interaction, and either the Hertz Mindlin or Walton Braun models.

Contact Temperature

The temperature at the point of contact between particle and particle or between particle and wall. This field function is available on contact, regardless of the Register Basic Contact Field Functions value. The temperature is calculated according to the theory in [98].

Function Name:	ContactTemperature
Dimensions:	Temperature
Default units:	K
Type:	Scalar
Activated by:	Energy, when particle is in contact

Contact Temperature 0|1

The temperature of one of the two particles or of a particle and a wall in a collision.

Function Name:	ContactTemperature0|1
Dimensions:	Temperature
Default units:	K
Type:	Scalar
Activated by:	Energy, Register Basic Contact Field Functions property is On when particle is in contact

Contact Time

When two particles or a particle and wall boundary make contact, that is, Contact Overlap is greater than zero, the contact time of the contact pair is accumulated until the pair is separated.

Contact Torque

Moment ${\mathbf{M}}_c$ in Eqn. (2961).

Contact Youngs Modulus 0|1

The Young's modulus for one of the two particles (0 or 1) in a collision.

Cylinder Height

The height of a cylindrical DEM particle. To access this field function, select the Cylindrical Particles model.

Cylinder Radius

The radius of a cylindrical DEM particle. To access this field function, select the Cylindrical Particles model.

Effective Particle Volume

The volume of a particle minus the overlapping volume beyond the plane(s) of intersection with any other particle(s).

Erosion Rate

The sum of Abrasive Wear Rate and Impact Wear Rate. It is the quantity $E_f$ in Eqn. (3306).

Impact Wear Rate

The rate at which material is being eroded from a boundary by direct impact. To access this field function, select the Impact Wear model.

Normal Bond Stress

The normal stress in a bond, used in damage and failure modeling. See ${\delta }_{\text{max}}$ in Eqn. (3292). To access this field function, select the Bonded Particles or Parallel Bonds model.

Parcel Axis Orientation i | j | k

The Parcel Axes Orientation are the vectors which represent how the three axes of the system local to the particle are transformed after the corresponding rotation is applied.

Parcel DEM Timestep

See Eqn. (3244) through Eqn. (3247). This relates to the particle model timescale, which, along with other conditions, contributes to the evaluation of the parcel time-step.

Parcel Halo Count

Used in debugging.

Parcel Halo Marker

Used in debugging.

Parcel Orientation

The orientation vector of the parcel, expressed as Euler angles.

Particle Angular Momentum

${\mathbf{I}}_p{\omega }_p$ . See Eqn. (2960).

Particle Angular Velocity

${\omega }_p$ in Eqn. (2960).

Particle Component Index

This field function displays the index numbers associated with the components of the particles (spheres for Particles Clumps or segments for Flexible Fiber). Each particle component has a unique index that distinguishes it.

Particle Connected Component Size

The number of spheres in the particle cluster to which the given particle belongs. Compare with the Bonded Component Size field function.

Particle Connected Components

The labels (integers) of particle clusters. These clusters are groups of particles that form a single connected network through particle-particle contact. Compare with the Bonded Components field function.

Particle Critical Velocity

The critical velocity of the particle $v_{\text{crit}}$ in Eqn. (3263) resulting from the force as estimated by the Hertz-Mindlin contact model. Once the particle exceeds this velocity, it has enough energy to exit the domain through a planar wall.

Particle Diameter

The particle diameter as that of a sphere of equal volume.

Particle Flow Rate

The rate at which particles flow along parcel tracks, ${\dot{n}}_{\pi }$ . (Steady)

Particle Moment Inertia

${\mathbf{\text{I}}}_p$ in Eqn. (2960). This quantity can be used for validation.

Particle Projected Area

The cross-sectional area of the particle orthogonal to the direction of the fluid velocity relative to the particle centroid. Each particle in a clump is treated separately; overlaps of cross-sections are not addressed. All other composite particles are treated as a unit and the projected area is numerically estimated. For polyhedral particles, the area is calculated by summing over the projections of each triangular face, avoiding double-counts.

Particle Projected Length

The average length of the particle parallel to the direction of the fluid velocity relative to the particle centroid. Each particle in a clump is treated separately. All other composite particles are treated as a unit and the projected length is numerically estimated. For polyhedral particles, the length is calculated by summing over the projections of each triangular face, avoiding double-counts.

Particle Residence Time

The “age” of particles as measured from time of injection.

Particle Rotation Kinetic Energy

Allows post-processing of the kinetic energy of the rotating particle.

Particle Volume Overlap

How much of the particle is obscured by the contact area.

Polyhedron Elongation Factor

An ordered triple of multipliers defining stretch factors (>1) or shrink factors (<1) for the template polyhedron. See Polyhedron Elongation Factor.

Tangential Bond Stress

The shear stress in the contact plane of a bond, used in damage and failure modeling. See ${\sigma }_{\text{max}}$ in Eqn. (3293). To access this field function, select the Bonded Particles or Parallel Bonds model.

Void Fraction

The fraction of the cell volume available to the fluid, unoccupied by a solid or dispersed phase.