Fully Automatic Hex Dominant Mesher

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• Fully Automatic Hex Dominant Mesher
• Paul Gilfrin
• Sharc Ltd

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About Sharc

• Sharc Ltd UK
• Developer of Harpoon
• Founded in 1997
• Distributors of Ensight
• Engineers with CFD/FEA experience
• Specialise in the integration of Harpoon within
  customers workflow to reduce lead time for the
  design process

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Design Process
Identifying a Need
Conducting Research
Defining the Problem
Narrowing the Research
Finding Alternative Solutions
Analysing Criteria
Analysing Alternative Solutions
Making a Decision
Presenting and Selling the Product
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Empowering the Engineer

• Analysing alternative solutions is an iterative
  process
• Amplifies decision making time

Finding Alternative Solutions
Analysing Criteria
Full CFD analysis 4 weeks Design change 2-3
days
Full CFD analysis 5 weeks Design change 1-2
weeks
Assumptions
Analysing Alternative Solutions
Making a Decision
Source EACC 2007 The CFD Process for
Aerodynamics at Volvo Cars using
HARPOON-FLUENT Zenitha Chroneer Volvo Car
Corporation
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Meshing Problem

• Meshing of complex geometries is one of the most
  labour intensive, repetitive processes in
  simulation today.
• Therefore meshing is the primary bottleneck to
  productivity gains

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Meshing Problem
Preparing input geometry Generating surface
mesh Growing volume mesh
Requires educated operator Extensive software
training Hours of repetitive work
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Harpoon
Extreme engineering problems require extreme
solutions.
Enter Harpoon, a fully automatic hex-dominant
mesher specifically designed to cope with the
most complex geometric entities.
Its speed and versatility give companies the
edge when it comes to shortening the time to
market
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Harpoon Process
Standard Pre-Processing
Harpoon
Minutes - Hours
Hours Days Weeks
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Harpoon Methodology
Approach consists of a modified Octree
method Body fitting mesh by means of
node-movement and cell manipulation/reconstruction
. No nasty cut cells.
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Why Change Your Process?

• Mesh faster
• Mesh more
• Mesh automatically
• Mesh the previously impossible

Harpoon
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Mesh Faster
Source data Jaguar XK8 model including
refinement zones
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Mesh Faster

• CAD Loaders
• Load CATIA, Unigraphics and IGES files directly
• Harpoon will retain layer association and
  separate into distinct parts
• Control tesselation settings through preferences

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Mesh Faster

• Dirty Geometry
• Mesh directly from CAD data

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Mesh Faster

• Dirty Geometry
• Tolerant to geometry errrors

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Mesh Faster

• Dirty Geometry
• Automatic hole detection/automatic filling

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Mesh Faster

• Dirty Geometry
• Leak Detection

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Mesh Faster

• Dirty Geometry
• Leak Detection/Mesh Trace

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Mesh Faster

• Simple setup
• Choose baselevel
• Apply levels to capture parts
• Name boundary surfaces
• Create refinement regions
• Mesh
• Check mesh
• Export to solver of choice

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Mesh Faster
Clearly, true to its word, Harpoon is very fast.
It builds the grid fast, but, frankly, more
importantly than that, you can set it up faster.
You can give it these .STL files and it just
builds the grid. If you dont like it, you can
change it. And, one minute later, change it
again. That kind of iteration takes weeks with a
conventional unstructured grid software package
for these geometries. Robert Kunz, Ph.D., Head
of the Computational Mechanics Division at
Pennsylvania State Universitys Applied Research
Laboratory
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Mesh Faster

• Faster Convergence
• The hexa-dominant mesh improves the convergence
  quality rate of the model, even with reduced
  mesh resolution
• Mass conservation residuals dropped by up 90
• Kinetic Energy residuals dropped by up to 20
• Convergence time was reduced by more than 30 for
  the initial condition case, up to 80 for the
  consecutive cases

Source www.sharc.co.uk Daimler Chrysler Pump
study. Comparing Harpoon mesh with previous full
tet method
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Mesh Faster

• Ducati Example
• 4.6 Million cell mesh
• 10 minute set up
• 3 minutes to mesh
• Solved using ANSYS Fluent 6.3
• K epsilon at 35m/s

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Mesh More

• Harpoon Speed up
• More runs
• Mesh at an earlier stage of the design process

30 millions cell mesh. Less than 2 hours to
generate on HP C800
The software enables us to undertake more
complex meshes in a much faster time, Anders
Jönson, Senior CFD Engineer at the Volvo Car
Corporation
The value of Harpoon, is that it provides a very
quick grid adequate for the level of fidelity of
prediction that were interested in to support
our preliminary design work. T. Alan Egolf,
Supervisor of Aerodynamic Methodology at Sikorsky
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Mesh More

• Results
• Daimler Chrysler pump study
• Excellent agreement was obtained using a Harpoon
  mesh, containing approximately 3M cells, at a
  fraction of the simulation effort required for a
  full tet mesh

Source www.sharc.co.uk
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Mesh More

• Results
• Achieve comparable results in considerably less
  time

Comparing to test results made in wind tunnel,
the separation line for the Harpoon mesh looks
more realistic Zenitha Chroneer, Volvo Car
Corporation
Source EACC 2007 The CFD Process for
Aerodynamics at Volvo Cars using
HARPOON-FLUENT Zenitha Chroneer Volvo Car
Corporation
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Mesh Automatically

• Simple to Use
• Minimal training required
• Intuitive GUI
• Config files for repetitive meshing
• Mesh then remesh to achieve the desired grid

Harpoon, compared to other mesh generation
software, doesnt require a steep learning
curvemaybe a week or two, Professor Len Imas
Stevens Institute of Technology
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Mesh Automatically

• Batch
• All features/settings can be invoked in batch.
• Including surface cell sizes, refinement areas,
  boundary/prism layers
• Config file is used to retain optimal settings
• Command line features for advanced mesh control
• 90 of meshes converge first time
• Perfect for optimisation projects

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Mesh Automatically

• New meshing algorithms
• New cell treatment improvements
• Extreme optimisation for difficult geometries

Harpoon 3.0 even better convergence!
Mercedes C class 20m/s K-E Realisable Moving Road
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Harpoon 2.4 Cell Based
Harpoon 2.4 Node Based
Harpoon 3.0 Cell Based
Harpoon 3.0 Node Based
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Mesh the previously impossible

• See results earlier in the design process

If the designer changes something we want to be
able to regrid quickly, which Harpoon allows us
to do, and get results in a timely manner so we
can have an impact on our schedule. T. Alan
Egolf Supervisor of Aerodynamic Methodology at
Sikorsky
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Mesh the previously impossible

• Wrap really dirty geometry
• De-feature
• Close large holes

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Mesh the previously impossible

• Match to a predefined surface mesh

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Mesh the previously impossible
Harpoon also enables us to support analysis in
new areas where the complexity of the required
meshing would have prevented our participation in
the past. Anders Jönson, Senior CFD Engineer at
the Volvo Car Corporation
Image Source EACC 2007 The CFD Process for
Aerodynamics at Volvo Cars using
HARPOON-FLUENT Zenitha Chroneer Volvo Car
Corporation
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Mesh the previously impossible
While using panel methods is reasonably fast and
inexpensive, it also allows a considerable amount
of the engineers subjectivity and speculation to
creep into the calculations. Thats because panel
methods cannot account for flow separation or
lift without user-selected models of these
phenomena.
Harpoon grids.. are cost-effective and provide
quick results that, when combined with FLUENT,
are far superior to traditional panel methods T.
Alan Egolf Supervisor of Aerodynamic Methodology
at Sikorsky
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Harpoons assets

• No need for a surface mesh
• No heavy CAD manipulation
• Tolerant to geometry errors the input geometry
  is only used as supporting geometry
• Reliable (always produces a mesh)
• Extremely fast (takes only a few minutes)
• Good quality valid cells
• Able to handle massive changes in scale
• Very easy to use

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Supported hardware platforms

• 64 bit architectures
• Linux SuSe 9.3
• Linux Red Hat WS
• HP-UX 11
• Solaris 8
• IRIX 6.5
• Itanium 2
• Windows 64,Vista

• 32 bit architectures
• Linux Red Hat 8
• Mac OSX 10.3
• Windows XP, 2000,Vista

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Output formats

• Geometries
• STL (save modified/wrapped geometry)
• Meshes

• NASTRAN
• Dytran
• LS-Dyna
• ANSYS
• ABAQUS
• STL
• Acusolve
• FOAM

• DTF
• Ensight
• Fluent
• Star-CD (CCM Soon)
• CFD
• Cobalt/AVUS
• CFX-5
• Gambit

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Who Can Benefit From Harpoon?
Any company looking for significant improvements
in development time

• Extremely quick 3D meshing
• Complex geometries
• Design optimisation
• Applicable to all areas of scientific computing

A huge improvement in terms of time and effort
spent compared to conventional methods
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Why Choose Sharc?
Sharc offers a personal approach which makes it
a very easy company to work with. Over the past
two years the team has always been very helpful,
demonstrating a willingness and ability to meet
our technical and business needs and responding
quickly when necessary. Anders Jönson, Senior
CFD Engineer at the Volvo Car Corporation
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Thank you

• Website
• www.sharc.co.uk
• Technical Enquiries
• paul_at_sharc.co.uk
• Tel [phone]