Aladdin Probe on: Meshing Infrastructure: Gary Miller: Discussion of the Sangria Project and the Ala

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Aladdin Probe onMeshing InfrastructureGary
Miller Discussion of the Sangria Project and
the Aladdin Meshing ProbeDavid Cardoze
Development of Moving Mesh Code.



Supported by NSF-ITR ACI 0086093
NSF-ITR Aladdin NSF-ITR Sangria
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The CMU SANGRIA Project

• Jim Antaki Pitt/CMU
• Guy Blelloch CS
• Omar Ghatttas MechEng
• Gary Miller CS
• Noel Walkington Math

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SANGRIA Project goals

• Develop parallel scalable geometric and numerical
  algorithms and software for simulating flows with
  dynamic interfaces
• Apply resulting tools to model microstructural
  blood flow
• Study microstructural models
• Study hemodynamic devices
• Understand hemodynamic basis of diseases

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Microstructural blood flow modeling

• Particularly difficult due to
• large relative motion between cells
• large deformations of cellular membranes

Electron micrograph of blood flow in
12mm ateriole (Rodin, 1972)
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Motivating problem 1 hemodynamic devices

• Streamliner left ventricular assist device
  under development at UPMC
• Led by Jim Antaki
• Numerous advantages
• Small size
• Reliability
• Low power consumption
• Less invasive
• Magnetic bearings
• Design challenge
• Overcome tendency to shear red blood cells
• First animal implantation July 1998 7X reduction
  in blood damage over previous prototype

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Motivating problem(s) 2hemodynamic disease
mechanisms

• Microcirculation is complex and poorly understood
  
• Abnormal microcirculation correlated with
• cardiovascular disorders
• diabetes
• cancer
• sickle-cell anemia
• Microstructural flow models can help elucidate
  disease mechanisms

Normal and sickle cells Sickle-Cell Information
Center Emory University School of
Medicine http//www.cc.emory.edu/PEDS/SICKLE
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Lagrangian vs. Eulerian description
Lagrangian (material) framework

• Lagrangian description of motion
• Interface representation embedded in material
  description of flow
• Interfaces are well-resolved and remain sharp
• Mesh convects and deforms with flow
• But mesh quickly becomes distorted, and dynamic
  remeshing becomes necessary
• Particularly difficult in parallel
• Eulerian description of motion
• Fixed grid
• Straightforward in parallel
• Interfaces approximately resolved through some
  other means

Eulerian (spatial) framework
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Algorithmic framework Lagrangian flow solver
aggressive remeshing
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Animation for Re100
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The Problem

• For 2D Meshing we have been able to generate
  polished meshing code for
• Delaunay Refinement
• Mesh Coarsening
• Parallel Meshing
• 3D May be too big for one school.
• Even if we can write our own is this the correct
  use of our time?
• Black box solutions most likely wont work.

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Some of the Code from CMU

• Geometric Partitioning Code ( Schwabe,Teng)
• Triangle Delaunay Refinement (Shewchuck)
• Parallel Delauany (Talmor, Hardwick)
• Divide-and-conquer with processor teams
  (Hardwick)
• Our 3d Meshing code (Pav)
• Our 2d Meshing code (Clemens)
• Simplicial Complex Interface (many)
• Tree based preconditioners for linear solvers
  (Gremban)
• Several projects in the pipe.

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Aladdin ProbeMeshing Infrastructure,
Co-Located with11th International Meshing
RoundtableSept 18, 2002 Cornell

Guy Blelloch, Gary Miller, Jonathan Shewchuk
Berkeley

Supported by NSF-ITR ACI 0086093
NSF-ITR Aladdin
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What is the Goal of this PROBE?

• To see if we can share in our development
  effort.
• Share code
• Share test data
• Share interfaces
• We hope to share with other members of the
  meshing community

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Why We have Organized this PROBE

• Many People, at least at Universities, were in
  the same boat as us.
• We talked to Steve Vavasis and Paul Chew at
  Cornell
• We talked to Jonathan Shewchuck at Berkeley.
• What we heard
• They had developed many new algorithms and
  techniques.
• They were developing code.
• The code was over many different languages.
• Their intended use of the code was very similar
  to ours.

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Talks

• Gary Miller (CMU) Introduction
• Steve Vavasis (CS Cornell)
• Ray-casting queries for curved geometry
• Carl Olliver-Gooch (Mech UBC) GRUMMP
• Generation and Refinement of
  Unstructured
• Mixed-Element Meshes in Parallel
• Lori Freitag (Argonne)
• Terascale Simulation Tools and Technology
  center
• Pat Knupp (Sandia) Mesquite
• Mesh Quality Improvement Toolkit
• William Jones (Langley)
• Open Framework for Unstructured Grid
  Generation
• Jonathan Shewchuk (Berkeley) Pyramid
• 3D version of Triangle
• Guy Blelloch (CMU) An Interface for
  Simplicial Complexes
• Mark Shephard (RPI) An Algorithm Oriented Mesh
  Database
• Discussion on sharing common infrastructure

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Some ideas for transfer among community (and
university)

• Repository of test data
• Common File formats (or code to translate among
  them)
• Nearly every mesher uses its own format for
  defining input
• (triangle, GRUMPP, Our code, Cornell code?)
• Common interfaces
• at the file level
• at the function level (conceptual or actual
  classes/signatures)

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Transferring outside the community

• Common code repository
• (for finished and documented code)
• Documented performance
• Survey articles/books
• Work with industry to try it out and get
  feedback

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What We have Learned from Workshop

• The meshing community is very large and diverse
• CAD
• Graphics
• Vision
• Finite Element
• The gap between prototype code and industry may
  be larger than we expected.
• More modest collaboration may be a better
  starting point.
• Say University to University

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Ongoing Work

• Interface for simplicial complexes (IMR
  03)Supports compressed representations
• Working with Jonathan Shewchuk to share code
• Support for moving mesh code

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Application to cellular flows
Cell membrane model finitely deforming elastic
membrane
Well-resolved thin lubricating layer prevents
cellular contact
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How Can this PROBE/Workshop Help?

• Bring together as many of the world experts and
  get from them
• Their experience
• Their ideas
• Determine what types of collaboration are
  possible
• Determine ongoing collaborations?