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© CADFEM 2017
Particle simulation with Rocky DEMCADFEM GmbH - Part 1
1
Luca Benvenuti
Simulation ist mehr als Software
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Agenda
• DEM: Theory and Applications
• DEM: Calibration and Customization
• DEM: More Efficient Processes
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• DEM: More Efficient Processes
• DEM: Longer Machine Life
• Multi-GPU Solver
• Non-Spherical Particle Shapes
• Fully integrated with ANSYS Software: Workbench & Mechanical
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DEM: Theory and Applications
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DEM: Granular Material
• Granular material • Solid macroscopic material • Dissipate energy by interaction, mostly
friction
• Many industries deal with particles• Mining• Pharmaceutical
Ship loading
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• Pharmaceutical• Agriculture• Cement• Transport• Chemical
• Discrete element method is used to model granular material• Particulate systems are difficult to
measure• Method to simulate a large number of
discrete objects• Classic mechanics wikipedia
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DEM: Predicting Particle Motion in Time
• Force and Torque balance for each particle
• Example: particle falling:
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wall
g
F = Force, m= mass, a = acceleration, g = acceleration due to gravity
Time = t, F = F body = mg
Time = t + 2Dt, F = F body + F surface = mg+ F(t)contact
Time = t + 3Dt, F = Fbody = mg
Time = t + Dt, F = F body = mg
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DEM: Contact forces
• Soft-sphere method is the most common, Cundall and Strack (1979)
• Particles can have a minimum overlap• Overlap is used to calculate elastic, d
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• Overlap is used to calculate elastic, plastic and frictional forces
• Normal and tangential directions
• Explicit time integration
d
,....),,,,(~
...),,,,(~
tan,
,
dssurface
normsurface
LF
CORELF
mmdd
dd&
&
Simulation ist mehr als Software
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DEM: Contact Models
• Normal Forces• Hysteretic Linear Spring, Linear Spring Dashpot, Hertzian Spring
Dashpot
• Tangential Forces
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• Tangential Forces• Linear Spring Coulomb Limit, Coulomb Limit, Mindlin-Deresiewicz
• Adhesive Forces• Constant, Linear, Leeds, Hertzian Spring Dashpot with JKR
Cohesion
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DEM: Calculation LoopSTART: Make geometry, create particles, create
neighbor list and contact list
DETERMINE FORCES & MOMENTS: Calculate sum of ALL forces & moments (Euler’s equation) acting on each particle
Fnet = Fbody + F surface = ma(Euler’s rotational equations of motion not shown for clarity)
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INTEGRATE STATES: Integrate in time to find new position
DV = FnetÂmÚ dt; Vnew = Vold + DVDx = VnewÚ dt; xnew = xold + DxV = velocity, x = position, dt = time step
END: Simulation end time or particles out of range? STOP
YesNo
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DEM: Industrial processes
• Separation / Mixing • Transport
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• Size reduction / Granulation • Storage
Source: https://en.wikipedia.org/wiki/Mechanical_screening
Source: https://en.wikipedia.org/wiki/Crusherhttps://en.wikipedia.org/wiki/Ball_mill
Source: https://en.wikipedia.org/wiki/Silo
Source: http://www.mechanicalengineeringblog.com/tag/bucket-elevator-how-it-works/
Simulation ist mehr als Software
https://en.wikipedia.org/wiki/Mechanical_screeninghttps://en.wikipedia.org/wiki/Crusherhttps://en.wikipedia.org/wiki/Ball_millhttps://en.wikipedia.org/wiki/Silohttp://www.mechanicalengineeringblog.com/tag/bucket
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DEM: How can modelling help?
• Increase equipment life and capacity
• Eliminate blockages
• Decrease product degradation
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• Reduce equipment noise, dust and power
• Define material trajectories
• Optimize belt tracking
• Minimize wear and maintenance
• …. and so on
Simulation ist mehr als Software
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DEM: ApplicationsWood chips (biomass handling) Tablets (pharmaceutical tablet coating)
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Rocks (truck dump) Wet and sticky ore (chute transfer in mining)
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DEM: Applications
• Eliminates need for external Multi-Body Dynamic Coupling (Unless geometry interactions are essential)
• Any geometry in Rocky can be a Free Body (motion can be constrained and boundary loads can be specified)
• Ballasted Layer Deformation
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• Ballasted Layer Deformation• Powder Compaction• Building in Landslide
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DEM: Applications: e.g. Excavator
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DEM: Applications: e.g. Ring Pan Mixer
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DEM: Applications: Dust Flow
• Airflow (Lattice-Boltzmann)• Simulation of a transfer chute with
airflow vectors enabled:• Show how dust and gas is affected
by particle flow
• Simulation of a transfer chute with NO airflow vectors enabled
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DEM: Calibration and Customization
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DEM: Calibration
• Determination of the relevant parameters in experiments
• Parameter identification by matching of real & virtual experiment
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Quelle: TUNRA BULK SOLIDS
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DEM: Calibration and Customization
• Calibrate material data• Automatic process• Consider statistics
• Customized results• Export particles position and orientation
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• Automatic generation of void-volume for CFD
ROCKY results
Exported particle results
Rebuild ROCKY results in CAD
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DEM: More Efficient Processes
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DEM: More Efficient Processes: Plow Mixer
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DEM: More Efficient Processes: Plow Mixer
• GUI based post-processing• Qualitative analyses:
• 3D visualization• Animations• Plots by color
• Quantitative analyses:
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• Quantitative analyses: • XY plots• time plots• histograms
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DEM: Longer Machine Life
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DEM: Longer Machine Life: Transfer Chutes Boundary Surface Wear
• Wall forces due to particles interactions (instantaneous and time average) are calculated
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• Shear Intensity X Belt Width • Impact Intensity X Belt Width
She
ar In
tens
ity (W
/m2 )
Impact Intensity (W
/m
Mean Shear Power (W/m2)
DEM: Longer Machine Life: Transfer Chutes Boundary Surface Wear
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She
ar In
tens
ity (W
/m Impact Intensity (W
/m2)
Belt Width (m)
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Multi-GPU Solver
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Multi-GPU Solver: Flexible Operating System
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Multi-GPU Solver: Tablet Coater
• Shared-parallel memory for both GPU and CPU
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• Commercial scale tablet coater rotating at 10 RPM• 242,000 custom convex particles with 222 vertices each• Advances in DEM Computing Which Improve Predictive Capability for Processes, AIChE 2016, Stomata et al.
Gaming cards Computing cards
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Multi-GPU Solver: High Shear Wet Granulation
• Scale up of high shear wet granulation • Advances in Discrete Element Modeling of high-shear wet granulation process using Rocky-DEM,
AIChE 2016, Pandey et al.
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• Scale up of high shear wet granulation• Suggestion: each 500k particles ‡ use 1 GPU (e.g. 2MM ‡ 4 GPU)
• 10 L granulator wall-clock-time-speed-up VS Particles-number-speed-up Relation
Multi-GPU Solver: High Shear Wet Granulation
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Scalability (and memory) for large particle numbers on multi-GPU
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Multi-GPU Solver: SAG Mill
• 9.8m SAG mill (Section: 0.5 m) • Fill: 25% (20% Ball)• Speed: 10.3 RPM
• 1MM spherical particles• Ore particles (0.17 – 0.01 m)
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• Ore particles (0.17 – 0.01 m)• Ball particles (0.10 – 0.055 m)
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• V-Blender is filled (Top-Bottom) and rotates at 10 RPM• Two particle groups of diferent materials are mixed• 300,000 spherical particles
Multi-GPU Solver: V-Blender
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Gaming cards Computing cards
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Non-Spherical Particle Shapes
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Non-Spherical Particle Shapes
• Default particle shapes in Rocky:
• Rocky shape examples:
Spherical Faceted Rounded Cylinder
Rounded Polygon
Rounded Polyhedron
Briquette
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• Rocky shape examples:
rock rice capsule pill
potato pea rod chip
orange barley metal coalSimulation ist mehr als Software
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Non-Spherical Particle Shapes: Does Shape Really Matter?
• Glued spheres • Polyhedral shape
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Almond Shape Tablet Representation
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Non-Spherical Particle Shapes: STL import
• Scan any shape and import it into Rocky:
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Non-Spherical Particle Shapes: Improved Concave Particle Simulation
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Non-Spherical Particle Shapes: Improved Concave Particle Simulation
• Concave shapes: Thin Potato Chip
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Non-Spherical Particle Shapes: Real case
• Screening/sorting• Real particle• Vibration movement
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Fully integrated with ANSYS SoftwareWorkbench & Mechanical
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ROCKY and ANSYS: Workbench integration
• Geometry parameterization using SpaceClaim (CAD)
• ROCKY parameters exposed into ANSYS Workbench environment
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• Automated project-level update mechanism
• DOE/Optimization/Sensitivity analysis using OptiSLang or DesingExplorer
Simulation ist mehr als Software
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ROCKY and ANSYS: Mechanical Coupling
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ROCKY and ANSYS: Mechanical Coupling – Static Structural
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• Rocky calculates the particle forces and the pressure (force over triangle area) on the boundary. The pressures components are then exported to Workbench Mechanical.
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ROCKY and ANSYS: Mechanical Coupling – Static Structural
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• Stresses and vibration analyses of ascreen in ANSYS
• Inputs come from Rocky simulation
Simulation ist mehr als Software
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ROCKY and ANSYS: Mechanical Coupling – Static Structural
ANSYS Mechanical results
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ANSYS SpaceClaim
Rocky resultsSimulation ist mehr als Software
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ROCKY and ANSYS: Mechanical Coupling – Transient Structural
• When there is boundary’s motion, Rocky translate and rotate the loads from the atual position to the initial position, so in WB Mechanical the strututure remais stopped while the loads moves.
• User defines the output frequency and
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• User defines the output frequency and the time range to export to the Mechanical
• In Mechanical, user has to setup the imported pressure to Components and fill the Tabular Data
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FULLY INTEGRATED with ANSYS tools
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