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EDEM Contact Models
A Contact Model describes how elements behave when they come into contact with each other.
Rolling Friction Contact Models
Rolling Friction is the resistive force that slows down the motion of a rolling object.
Type C Rolling Friction Model
The Type C Rolling Friction contact model, proposed by Ai et al. (2011), is an extension of the Standard Rolling Friction model.

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.
  - Standard Rolling Friction Model
    The Standard Rolling friction contact model is used in simulations where a torque is applied to the contacting surfaces where rolling friction is important.
  - Type C Rolling Friction Model
    The Type C Rolling Friction contact model, proposed by Ai et al. (2011), is an extension of the Standard Rolling Friction model.
  - RVD Rolling Friction Model
    The RVD Rolling Friction contact model offers an alternative friction calculation to the Standard EDEM Rolling Friction model.
- 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.
- 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.

Type C Rolling Friction Model

The Type C Rolling Friction contact model, proposed by Ai et al. (2011), is an extension of the Standard Rolling Friction model.

This model includes a non-viscous term in the damping torque equation.

M_{r} = M_{r}^{k} + M_{r}^{d}

Where M_r is the total damping torque vector, M_r^k is the non-viscous damping torque vector and M_r^d is the viscous damping torque vector. The non-viscous damping torque vector is a function of the relative particle rotation angle and the rolling stiffness as defined in Equations 2 and 3.

M_{r}^{k} = - K_{r} θ_{r}

k_{r} = λ k_{n} μ_{r}^{2} R_{r}^{2}

|M_{r}^{k}| \leq μ_{r} R_{r} F_{n}

Where k_r is the rolling stiffness, θ_r is the relative rotation angle, R_r is the equivalent rolling radius, k_n is the normal contact stiffness and μ_r is the Coefficient of Rolling Friction.

Note: The non-viscous torque magnitude is limited according to Equation 4, where F_n is the normal contact force.

The viscous damping torque vector is defined in Equation 5 and is a function of the relative rotational velocity vector at the contact point and the rolling viscous damping ratio.

m_{r}^{d} = - 2 η \sqrt{I_{r} k_{r}} ω

Where η is the rolling viscous damping ratio, I_r is the equivalent moment of inertia for the rotational vibration mode about the contact point, and ω is the relative rotational velocity vector at the contact point.

The viscous damping torque is only applied if the non-viscous torque magnitude is below the limit as defined in Equation 4. In cases where significant non-viscous rolling resistance is expected at particle contacts, such as when contact forces are high or the modeled material consists of predominantly angular particles, the use of Type C Rolling Friction may result in a more physically accurate behavior and greater stability of the EDEM model.