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EDEM - Introduction

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Discrete Element Modelling a way of simulating discrete matter

What is DEM?

DEM captures the dualnature of granular mediawhich behaves both likea solid and a fluid

The bulk behavior emergesfrom the collectiveinteraction of eachindividual object

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1960s: Existing continuum models have discontinuitiesintroduced into them

1971: First recognizable form of DEM for looking at rockmechanics problems

1979: Extended to granular material (not just rock)

1992: DEM defined as any computer program that:

(i) Allows finite displacement, rotation, and detachment of discretebodies

(ii) Recognizes new contacts as the calculation progresses

Throughout the late 90s and early 00s, the number ofpublications referencing DEM grows exponentially

History of DEM

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Over 70% of industrial processes involve particles BUT

The majority of particle handling and processing operations areempirically designed

Measurement and control is difficult and costly.

EDEM is used by engineers worldwide to increase profits by:

Reducing the need for physical prototypes

Troubleshooting operational problems

Designing more efficient processes by providing hard-to-measureinformation on bulk and particle-scale behavior

Saving expensive trial and error

Why use EDEM?

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EDEM = Engineering Discrete Element Method:

Easy-to-use

Graphical User Interface

CAD compatible

State-of-the-art DEM solver

Powerful DEM data visualization & analysis toolkit

Couples with ANSYS CFD and ANSYS FEA

EDEM

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1: Create materials, particles, geometry and physics models usingthe EDEM Creator

Integrated Environment

2: Define run-time and simulation settings andprocess the simulation using the Simulator

3: Use the Analyst to visualize your results,create animations and videos, graph theresults and export data

PAGE 6Particles

Prototype properties of mass, volume andinertia are calculated automatically from thesphere positions and sizes;

A CAD geometry can be imported to fit the multi-sphere particle;

Particle properties can also be calculated fromthe CAD template;

Able to simulate particles of any format;

Simulate adhesion and cohesion: captureparticle agglomeration and clogging.

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Particle size distribution can be defined based on the particleprototype

Particles have static properties that cannot be changed duringthe simulation

e.g. mass, volume, moments of inertia

Particles have variable quantities that change as the simulationprogresses

e.g. force, torque, velocity, angular velocity

Particles

Example results of a normaldistribution of mass-scaled

particles

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Geometry can be imported from a CAD file (IGES, STEP, ProE,FLUENT Mesh, STL, ACIS, Parasolid and Catia);

EDEM can create basic shapes such as cylinders, cones,rectangles and polygons;

Dynamics (translations, rotations) can be applied to geometrysections;

Geometry is automatically meshed into triangular elementswhen imported;

Geometry mesh elements have variable quantities such asforce, torque, velocity and angular velocity.

Geometry

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A particle factoryis used to introduce particles into a simulation

The particle factory generates particles from the defined particleprototype

Particles can be generated on any virtual geometry surface or

inside a geometry volume The particle factory can also define:

Particle prototype, size, position, velocity orientation, angular velocity

Factories

A virtual factory surfaceshown generating variedsized particles

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During processing, the EDEM domain is split into a grid

The grid is used to speed up the detection of contacts betweenelements

Optimum calculation speed varies between a grid size of 2xminimum sphere radius to 6x minimum sphere radius

2-3 RMin is preferable

A smaller RMin size generates more grid cells. This requiresmore memory (RAM)

EDEM Grid

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Using the grid settings, EDEM performs an analysis loop todetect contacts between elements

Particle-to-particle and particle-to-geometry contacts are detected

Once a contact between two elements has been detected, contactproperties (such as particle prototype, size, and relative velocity)

are passed to the contact model to calculate the force

Contact Detection

Once the force is calculated, theparticles and geometry elementsare re-positioned and the contact

detection loop re-started

Contact vector shown

between two spheres

PAGE 12Analysis Loop

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Able to simulate any equipment;

Able to simulate particles of any shape;

Simulate cohesion and adhesion to capture agglomeration;

Real size particle simulation:

Reach up to 4 million particles;

Particle scale up is unnecessary for most of the cases.

Integrated environment:

Easy set up

Powerful analyses tools

Complex geometry movement:

Rotation and translation;

Moving plane model (conveyors).

EDEM Advantages

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Wear reduction:

Chutes, conveyors, off-road trucks, screens, mills, crushers, etc

Correct material distribution:

Screens, blast furnaces, conveyors, mills.

Correct the flow:

Chutes, mills, reclaimers, silos (rat holes, avalanche), conveyors(misalignment)

Reduce dust generation:

Chutes, conveyors

Avoid clogging, pillage.

Improve efficiency!

Reduce costs!

Faster, cheaper and smarter solutions!

Some direct results...