Simulation of Ceramic DPF Media, Soot Deposition and Pressure Simulation of Ceramic DPF Media, Soot Deposition and Pressure Simulation of Ceramic DPF Media, Soot Deposition and Pressure Simulation of Ceramic DPF Media, Soot Deposition and Pressure
Drop Evolution UsingDrop Evolution UsingDrop Evolution UsingDrop Evolution Using
Dr. Stefan Rief
Dipl.-Math. Kilian Schmidt
Dr. Andreas Wiegmann
FraunhoferFraunhoferFraunhoferFraunhofer----Institut Institut Institut Institut
TechnoTechnoTechnoTechno---- und Wirtschaftsmathematik, Kaiserslauternund Wirtschaftsmathematik, Kaiserslauternund Wirtschaftsmathematik, Kaiserslauternund Wirtschaftsmathematik, Kaiserslautern
GermanyGermanyGermanyGermany
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Outline
1. Virtual Structure Generation of DPFs
• Fibrous Structures
• Sinter Materials
2. Simulation of DPF Properties
• Modeling and Simulation Approach
• Example 1: Design Study of DPF Filters
• Example 2: Micro Sieves
3. Summary
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1. Virtual Structure Generation of DPFs
Multilayer Virtual Fibrous Structure Multilayer Virtual Fibrous Structure Multilayer Virtual Fibrous Structure Multilayer Virtual Fibrous Structure
• Stochastic generation of the structure with
guaranteed adjustable properties, e.g.
– Distribution of fiber diameters and cross
sections
– Fiber orientation
– Porosity
– Layer thickness
– …
• Stacking of layers with different parameters
• Use of highly flexible voxel meshes
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1. Virtual Structure Generation of DPFs
Virtual Sinter StructureVirtual Sinter StructureVirtual Sinter StructureVirtual Sinter Structure
• Stochastic generation based on
– Packings of spheres
– Morphological operations (to generate
sinter necks)
• Packings of spheres selected to match the initial
grain size distribution of the sinter process
• Approach was applied in an industrial project
when no tomographies were available due to
– Difficult preprocessing of samples
– Too coarse resolution
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1. Virtual Structure Generation of DPFs
SEM image Virtual Reconstruction
Basic shapes I
Inversion
Erosion
“Sand”
Basic shapes II
Inversion
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1. Virtual Structure Generation of DPFs
Quality Measures for Virtual StructuresQuality Measures for Virtual StructuresQuality Measures for Virtual StructuresQuality Measures for Virtual Structures
• “The Eye”
• Porosity, specific surface area
• Chord length distribution
• Pore size analysis
• Flow properties, e.g. effective permeability or
flow resistivity
• Bubble point, capillary pressure curves
• Filtration properties
• Acoustic properties
Comparison of Effective Flow Properties
0
0,5
1
1,5
2
2,5
200 400 600 800 1000 1200 1400 1600 1800 2000 2200 2400 2600 2800 3000 3200
Pressure Drop [Pa]
Ve
loc
ity
[m
/s]
Simulation
Experiment
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2. Simulation of DPF Properties
Flow
Single Fiber Simulation
1. Choose initial structural parameters
2. Generate / modify structure
3. Solve CFD problem
4. Compute particle transport and deposition
5. Compute filtration efficiency and pressure drop
6. Choose new material parameters
OPTIMIZATION
Simulation of Filtration ProcessesSimulation of Filtration ProcessesSimulation of Filtration ProcessesSimulation of Filtration Processes
LIFETIME
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2. Simulation of DPF Properties
Flow simulation is based on NavierFlow simulation is based on NavierFlow simulation is based on NavierFlow simulation is based on Navier----StokesStokesStokesStokes----Brinkmann equationsBrinkmann equationsBrinkmann equationsBrinkmann equations
Henry Darcy (1803-1858)
RemarkRemarkRemarkRemark
• convective term optional -> fast flow
• Brinkmann term optional ->subgrid particle deposition and effectiveporous media
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2. Simulation of DPF Properties
Lagrangian Particle TransportLagrangian Particle TransportLagrangian Particle TransportLagrangian Particle Transport
Particle DepositionParticle DepositionParticle DepositionParticle Deposition
• Collision handling
• Adhesion model
Modification of GeometryModification of GeometryModification of GeometryModification of Geometry
• Solid deposition model (particles resolved by voxels)
• Porous deposition model -> small particles are handled as porous media
• Porous deposition model + subvoxel collision handling
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2. Simulation of DPF Properties
Particulate filter medium with fiber layer
Design Study of a Diesel Particulate FilterDesign Study of a Diesel Particulate FilterDesign Study of a Diesel Particulate FilterDesign Study of a Diesel Particulate Filter
• What is the effect of an additional fibrous layer on top of a sintered substrate ?
• Soot particles (~80nm) are much smaller than
voxels (1µm) -> porous deposition model
• Navier-Stokes-Brinkmann model to handle free and porous flow
• Permeability and maximum degree of filling of porous voxels are determined by high resolution
single fiber experiments
• Several hundreds of millions of particles are needed for a lifetime computation
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2. Simulation of DPF Properties
Cut-Out of Soot LayerHigh Resolution Single Fiber Simulation
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2. Simulation of DPF Properties
Micro Sieves Micro Sieves Micro Sieves Micro Sieves –––– Study of Different Deposition ModelsStudy of Different Deposition ModelsStudy of Different Deposition ModelsStudy of Different Deposition Models
• 20 µm x 20 µm holes in periodic arrangement
• Soot particles (~80nm) are much smaller than
voxels (1µm)
• Navier-Stokes-Brinkmann model to handle free and porous flow
• Comparison of porous voxel approach w/o subvoxel collision handling
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2. Simulation of DPF Properties
Porous Deposition Model Porous Deposition Model with Subvoxel Collision Handling
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3. Summary (and more …)
---- FiberFiberFiberFiberGeoGeoGeoGeo,,,, SinterSinterSinterSinterGeoGeoGeoGeo, WeaveWeaveWeaveWeaveGeoGeoGeoGeo, GridGridGridGridGeoGeoGeoGeo, , , , PackPackPackPackGeoGeoGeoGeo (Structure generation)
---- ProcessProcessProcessProcessGeoGeoGeoGeo (3d image processing)
---- LayerLayerLayerLayerGeoGeoGeoGeo (building media stacks)
---- ImportImportImportImportGeoGeoGeoGeo (Tomography, STL, etc.)
---- PoroPoroPoroPoroDictDictDictDict (Pore size analysis)
---- FlowFlowFlowFlowDictDictDictDict (Flow properties)
---- FilterFilterFilterFilterDictDictDictDict (Filtration)
---- DiffuDiffuDiffuDiffuDictDictDictDict (Effective diffusion)
---- SatuSatuSatuSatuDictDictDictDict (Capillary pressure curves)
---- ElastoElastoElastoElastoDictDictDictDict (Effective elasticity)
---- ThermoThermoThermoThermoDictDictDictDict (Heat conductivity)
---- ExportExportExportExportGeoGeoGeoGeo (Fluent, Abaqus)
---- AcoustoAcoustoAcoustoAcoustoDictDictDictDict (acoustic absorption properties)
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GeoDict Development Teams
The FiberGeo TeamAndreas WiegmannKatja SchladitzJoachim Ohser
Hans-Karl HummelPetra Baumann
WeaveGeo & PleatGeoAndreas Wiegmann
The SinterGeo TeamKilian SchmidtNorman Ettrich
The ElastoDict TeamHeiko Andrä
Dimiter StoyanovAndreas Wiegmann
Vita RutkaDonatas Elvikis
GridGeo & PackGeoAndreas Wiegmann
FlowDict Lattice Boltzmann Team
Dirk KehrwaldPeter KleinDirk MertenKonrad SteinerIrina Ginzburg
Doris Reinel-Bitzer
FlowFlowFlowFlowDictDictDictDict EJ Solver TeamAndreas WiegmannLiping ChengAivars ZemitisDonatas Elvikis
Vita RutkaQing Zhang
The FilterDict TeamStefan RiefKilian SchmidtArnulf Latz
Andreas WiegmannChristian WagnerRolf Westerteiger
The SatuDict TeamJürgen BeckerVolker Schulz
Andreas WiegmannRolf Westerteiger
The RenderGeo TeamsCarsten LojewskiRolf WesterteigerMatthias Groß
The GeoDict TeamAndreas WiegmannJürgen BeckerKilian SchmidtHeiko Andrä
Ashok Kumar VaikuntamRolf WesterteigerChristian WagnerMohammed Alam
Jianping Shen
The PoroDict TeamAndreas WiegmannJürgen BeckerRolf Westerteiger
The PleatDict TeamAndreas Wiegmann
Oleg IlievStefan Rief