http://cs.swan.ac.uk/ the search for swirl and tumble motion robert s. laramee department of...
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http://cs.swan.ac.uk/
The Search for Swirl and Tumble Motion
Robert S. LarameeDepartment of Computer Science
Swansea University
Wales, UK
2 The Search for Swirl and Tumble Motion
Robert S. [email protected]
Outline Problem description: swirl and tumble motion Flow visualization classification:
direct geometric texture-based feature-based
The great search 2D 2.5D (surfaces) 3D steady and unsteady flow
Summary and conclusions
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Swirl and Tumble Motion swirl motion:
characterized by motion about cylinder-aligned axis
more stable (easier)
tumble motion: characterized by motion about axis orthogonal to cylinder
unstable, more difficult
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Robert S. [email protected]
Swirl and Tumble MotionAchieving ideal patterns of motion leads to optimal
mixing (of air and fuel) conditions e.g., higher exhaust/gas ratio (EGR) decrease in fuel consumption lower emissions
1. Can visualization provide insight into or verify characteristic shape/behavior of flow?
2. What tools help to visualize swirl/tumble motion?3. Where (in the combustion chamber) are ideal
ideal flow pattern not being realized?
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Flow Visualization Classification1. direct: overview of vector
field, minimal computation, e.g. glyphs, color map
2. texture-based: complete coverage, more computation time, implementation time, e.g., Spot Noise, LIC
3. geometric: compute a discrete object whose geometry reflects flow characteristics, e.g. streamlines
4. feature-based: interesting subsets of the flow are first extracted
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The Great SearchGeometric Texture-
basedFeature-based
2D
2.5D
3D & hybrid
Both steady and unsteady flow!
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2D Slices, Geometric Flow Visualization
3D streamlets for visualization of swirl motion:
Coverage is incomplete
Seeding an issue
Resampling used
swirl motion good, although
off-center
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2D Slices, Geometric Flow Visualization
Streamlines and tumble motion
Implemented via dye injection:
Coverage incomplete
Some flow features highlighted
Applicable to 3D Downstream
direction shown
non-ideal tumble motion, saddle
point
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2D Slices, Texture-Based Flow VisualizationTexture-based flow
visualization and swirl motion:
Image-Based Flow Visualization (IBFV) [Van Wijk 02]
Complete coverage Flow features shown Hard to apply in 3D downstream direction
shown
swirl behaviour evident
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Robert S. [email protected]
2D Slices, Texture-Based Flow Visualization
Texture-based flow visualization and tumble motion:
Complete coverage Flow features shown Difficult to apply to 3D Downstream direction
shown
tumble behavior non-ideal
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2.5D, Geometric Flow VisualizationDye injection on
surface (tumble motion):
Incomplete coverage Flow features depend
on seeding Applies to 3D Downstream direction
shown
tumble motion: separatrix
highlighted
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Robert S. [email protected]
2.5D, Geometric Flow VisualizationTimelines on surface: Incomplete coverage Flow features depend
on seeding Applicable to 3D Downstream direction
shown in animation
tumble motion: divergent and
convergent areas of the flow highlighted
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Robert S. [email protected]
2.5D, Texture-Based Flow Visualization
Texture-based approach at surface:
Image Space Advection (ISA) [Laramee et al. 04]
Complete coverage Flow features visible Difficult to apply in 3D Downstream direction
shown
swirl motion: generally good at surface (w/
exceptions)
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Robert S. [email protected]
2.5D, Texture-Based Flow Visualization
Texture-based approach on surface:
ISA Complete coverage Flow features visible Difficult to apply in 3D Downstream direction
shown
tumble motion: rotation off-center?
saddle point shown
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Robert S. [email protected]
3D & Hybrid, Geometric Flow Visualization
3D streamlines Incomplete coverage Flow features
depend on seeding Appropriate for 3D Downstream
direction sometimes shown
swirl motion: (generally)
prevalent inside combustion
chamber
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3D & Hybrid, Geometric and Texture-Based Flow Visualization
Geometric and texture-based flow visualization on isosurfaces
Incomplete coverage Flow features depend on
placement Appropriate for 3D Downstream direction
shown
swirl motion: prevalent inside combustion
chamber, non-ideal motion also prevalant
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Robert S. [email protected]
3D & Hybrid, Geometric and Texture-Based Flow Visualization
Geometric and texture-based flow visualization on isosurfaces
Incomplete coverage Features shown depend on
placement Applicable to 3D Downstream direction
shown
tumble motion: axis of rotation is off center,
cross between two ideals
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Robert S. [email protected]
2.5D Feature-Based Flow Visualization
2.5D Feature-Based Swirl Visualization
Topological skeleton of flow is extracted explicitly
Features shown automatically
Applicable to 3D Complete coverage Downstream direction not
shown
swirl motion: very complex
near top of chamber
red = saddle
blue = sink
green = source
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Robert S. [email protected]
3D, Unsteady Geometric Flow Visualization
3D, Unsteady Geometric Tumble Visualization
Pathlets seeded at inlet Features depend on
seeding Applicable to 3D Incomplete coverage Downstream direction
shown
tumble motion: difficult to
observe
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Robert S. [email protected]
3D, Feature-Based Flow Visualization
3D, Feature-Based Swirl Visualization
Boundary topology + 3D vortex core lines
Features extracted automatically
Applicable to 3D Incomplete coverage Downstream direction not
shown
Swirl motion: candidate
swirl axis off-center
red = saddle
blue = sink
green = source
21 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Unsteady Feature-Based Flow Visualization
3D, Unsteady Feature-Based Tumble Visualization
Boundary topology extracted + 3D vortex core lines
Features extracted automatically Applicable to 3D Incomplete coverage Downstream direction not shown
tumble motion: very transient
red = saddle
blue = sink
green = source
22 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Feature-Based Flow Visualization
3D, Feature-Based Swirl Visualization
Boundary topology + 3D vortex core regions-lamda 2 transfer function
Features extracted automatically, resampling necessary
Applicable to 3D Incomplete coverage Downstream direction not shown
Swirl motion: candidate
swirl axis off-center
red = saddle
blue = sink
green = source
23 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Unsteady Feature-Based Flow Visualization
3D, Unsteady Feature-Based Tumble Visualization
Boundary topology extracted + 3D vortex core regions –lambda 2 transfer function
Features extracted automatically, resampling necessary
Applicable to 3D Incomplete coverage Downstream direction not shown
tumble motion: complex!
candidate axis is revealed
red = saddle
blue = sink
green = source
24 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Unsteady Feature-Based Flow Visualization
Tumble Visualization-more difficult to visualize
Volume rendering of 3D vortex core regions –lambda 2 + helicity
Features extracted automatically, resampling necessary
Applicable to 3D Incomplete coverage Downstream direction not shown
tumble motion: candidate axis is
more clearly revealed
25 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Unsteady Feature-Based Flow Visualization
Tumble Motion and Hybrid Visualizations
Volume rendering of 3D vortex core regions –lambda 2 in combination with particles
Features extracted automatically, resampling necessary
Applicable to 3D Incomplete coverage Downstream direction shown
tumble motion: very transient, most effective up to
this point
26 The Search for Swirl and Tumble Motion
Robert S. [email protected]
3D, Unsteady Feature-Based Flow Visualization
Tumble Motion and Hybrid Visualizations
3D vortex core lines in combination with particles
Features extracted automatically Applicable to 3D Incomplete coverage Downstream direction shown
tumble motion: very transient, most effective up to
this point
27 The Search for Swirl and Tumble Motion
Robert S. [email protected]
2.5D, Feature-Based Flow Visualization
Tumble Motion and Periodic Orbit Extraction
Automatic periodic orbit extraction
Applicable to 3D Incomplete coverage Downstream direction shown (in
animation)
tumble motion: extracted directly,
questions with interpretation
28 The Search for Swirl and Tumble Motion
Robert S. [email protected]
Summary and Conclusions We have presented the most
comprehensive search for swirl and tumble motion ever…
The search continues! Future feature-based flow visualization
techniques need to be able to extract user-defined features directly, in 3D, and be applicable to unsteady flow
29 The Search for Swirl and Tumble Motion
Robert S. [email protected]
AcknowledgementsThanks to the following people:
Guoning ChenChristoph GarthHans HagenHelwig HauserKonstantin MischaikowJuergen SchneiderXavier TricocheDaniel WeiskopfEugene Zhang
Thank you for your attention!Questions?