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Particle simulation with Rocky DEMCADFEM GmbH - Part 1

1

Luca Benvenuti

Simulation ist mehr als Software

Agenda

• DEM: Theory and Applications

• DEM: Calibration and Customization

• DEM: More Efficient Processes

© CADFEM 2017 Simulation ist mehr als Software 2

• 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

Simulation ist mehr als Software 3

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

4Simulation ist mehr als Software

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 bodyÂ = mg

Time = t + 2Dt, F = F body + F surfaceÂ = mg+ F(t)contact

Time = t + 3Dt, F = FbodyÂ = mg

Time = t + Dt, F = F bodyÂ = mg


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&

&


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


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 = FbodyÂ + 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


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/


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

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


DEM: ApplicationsWood chips (biomass handling) Tablets (pharmaceutical tablet coating)

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Rocks (truck dump) Wet and sticky ore (chute transfer in mining)


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


DEM: Applications: e.g. Excavator

© CADFEM 2017 13Simulation ist mehr als Software

DEM: Applications: e.g. Ring Pan Mixer


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


DEM: Calibration

• Determination of the relevant parameters in experiments

• Parameter identification by matching of real & virtual experiment


Quelle: TUNRA BULK SOLIDS

DEM: Calibration and Customization

• Calibrate material data• Automatic process• Consider statistics

• Customized results• Export particles position and orientation


• 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


DEM: More Efficient Processes: Plow Mixer


DEM: More Efficient Processes: Plow Mixer

• GUI based post-processing• Qualitative analyses:

• 3D visualization• Animations• Plots by color

• Quantitative analyses:


• Quantitative analyses: • XY plots• time plots• histograms


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DEM: Longer Machine Life


DEM: Longer Machine Life: Transfer Chutes Boundary Surface Wear

• Wall forces due to particles interactions (instantaneous and time average) are calculated


• 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

© CADFEM 2017

She

ar In

tens

ity (W

/m Impact Intensity (W

/m2)

Belt Width (m)



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Multi-GPU Solver


Multi-GPU Solver: Flexible Operating System


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


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.


• 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


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)


• 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


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

Non-Spherical Particle Shapes: Does Shape Really Matter?

• Glued spheres • Polyhedral shape

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Almond Shape Tablet Representation


Non-Spherical Particle Shapes: STL import

• Scan any shape and import it into Rocky:


Non-Spherical Particle Shapes: Improved Concave Particle Simulation


Non-Spherical Particle Shapes: Improved Concave Particle Simulation

• Concave shapes: Thin Potato Chip


Non-Spherical Particle Shapes: Real case

• Screening/sorting• Real particle• Vibration movement


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


ROCKY and ANSYS: Mechanical Coupling


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.


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


particle simulation with rocky dem titelmasterformat durch ...€¦ · • ball particles (0.10...

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