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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...