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EDEM Contact Models
A Contact Model describes how elements behave when they come into contact with each other.
Additional Contact Models
You can also add Additional contact models to a simulation.
Tribocharging Model
The Tribocharging contact model allows you to simulate a change of charge of particles within a material after they come into contact with a different material.

Welcome
What's New
New features and enhancements available in EDEM.
Release Notes
This document contains information about the EDEM release, such as key features and enhancements, bug fixes, and known issues.
About EDEM
EDEM is a high-performance simulation software for bulk and granular materials.
Get Started with EDEM
The EDEM user interface comprises three icons for each simulation component - Creator, Simulator, and Analyst.
EDEM Creator
EDEM Creator is the pre-processor for creating an EDEM simulation model, including setting up equipment and defining the generation of bulk materials.
EDEM Simulator
EDEM Simulator is a powerful solver used for fast and efficient simulations.
EDEM Analyst
EDEM Analyst is the post-processor used to analyze and visualize the results of your simulation.
EDEM Contact Models
A Contact Model describes how elements behave when they come into contact with each other.
- Base Contact Models
  Base Contact models define the physical collision between particle materials or particles and geometries.
- Rolling Friction Contact Models
  Rolling Friction is the resistive force that slows down the motion of a rolling object.
- Spinning Friction Contact Model
  The Spinning Friction contact model is used to account for the friction that would occur if a particle face is rotating against another particle or Geometry.
- Additional Contact Models
  You can also add Additional contact models to a simulation.
  - Archard Wear Model
    The Archard Wear contact model extends any Base Model to provide an estimation of wear depth for geometry surfaces.
  - Relative Wear Model
    The Relative Wear contact model is used to identify regions of high impact (normal) and abrasive (tangential) wear on the equipment within a simulation.
  - Oka Wear Model
    The Oka or Impact Wear contact model extends any Base Model to give an estimation of erosion depth for Geometry surfaces due to particle impacts.
  - Bonding V2 Model
    The Bonding V2 contact model is used to bond particles with a finite-sized 'glue' bond.
  - Linear Cohesion V2 Model
    The Linear Cohesion V2 contact model is an enhancement of the Linear Cohesion model and was made accessible for the first time in EDEM version 2017.2) owing to its improved performance for non-uniform particle size distributions.
  - Heat Conduction Model
    The Heat Conduction contact model calculates the heat flux based on the relative temperatures and the particle overlap.
  - Tribocharging Model
    The Tribocharging contact model allows you to simulate a change of charge of particles within a material after they come into contact with a different material.
  - Electrostatics Model
    The Electrostatics contact model allows you to add electrostatic forces to the existing kinematic forces in the Particle Body Force section.
  - Spray Coating Model
    The Spray Coating contact model adds the mass of one type of particle to another upon contact.
  - Tavares UFRJ Breakage Model
    The Tavares UFRJ Breakage contact model captures the various body breakage mechanisms that occur during particle collisions.
  - Wet Mixing Model
    The Wet Mixing contact model allows you to add particles with moisture content (defined in the factory settings) to a simulation.
- Particle Body Force Contact Models
  You can define a particle body force to act on particles when a specified condition is met, when particles are in certain positions, or are traveling at a specified velocity.
- Plug-in Contact Models
  You can add Plug-in contact models to a simulation.
- Field Data Manager
  Field Data Manager allows you to import and manage field data for use in a Custom model (typically, a Particle Body Force).
- Contact Model and GPU Device Compatibility
  The Multi-Sphere solver can run on two different engines such as CPU and CUDA.
EDEM Cal Utility
EDEM Cal is a utility which works with EDEM and is designed to assist in performing calibration.
GPU CUDA Guide
The EDEM CUDA GPU module uses the latest General Purpose Computing on Graphical Processing Units (GPU) technology.
Programming Guide
The EDEM Programming Guide describes the EDEM API.
Coupling Interface Programming Guide
The Coupling Interface Programming Guide provides an overview of how to use the EDEM Coupling Interface to couple with a generic CFD code and/or Multi Body dynamics codes.
EDEMpy
EDEMpy is a Python library for accessing EDEM data from .h5 files (the underlying EDEM file format). EDEMpy does not require prior knowledge of advanced programming.
EDEM Solver Capabilities
EDEM contains four solver engines.
Appendix
This section provides additional information about how to estimate simulation time, supported EDEM File types, attribute definitions, and so on.
EDEM Terminology
Definitions of terms used in EDEM.
References and Bibliography
This section cites the contributions made by various authors and sources that have been used as reference material for EDEM, and the specifics of how they have been applied can be found in the individual contact model sections.

Tribocharging Model

The Tribocharging contact model allows you to simulate a change of charge of particles within a material after they come into contact with a different material.

For repeated contacts, a saturation charge level is reached which is a function of both charge generation and dissipation processes. In most ESD (electrostatic discharge) problems, triboelectrification is the prime charge generation process.

You must first specify the work function. Tribocharging (triboelectric charging) will occur if the work functions of two materials differ. There will not be a charge transfer if the work functions remain the same.

The following equation is based on work by Greason (2000) and describes the change in charge:

\frac{d q}{d t} = α (q_{s} - q) - β_{q}

Where q is a charge of a sphere at time t, α and β are the time constants of the charge generation and dissipation respectively. α is in the range of 0.02–0.085 s-1 for polymers and in the range 0.002–0.005 s-1 for metals. β is neglected in calculations because charge dissipation through atmospheric ion impingement is slow (Hogue, et al. 2007).

And q_s is a saturation charge defined as:

q_{s} = σ A_{s}

Where σ is a surface charge density which is approximately equal to 2.66e-5 cm-2 for air standard pressure and temperature, and As is the surface area of a particle.