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Robert S. LarameeDepartment of Computer Science
University of Wales, Swansea, UK
Effective Visualization of Heat Transfer
2 Effective Visualization of Heat [email protected]
OutlineOutline Cooling jacket design: ideal flow and design goals Visualization classification: direct, geometric,
texture-based, and feature-based flow visualization: both automatic and interactive
Applying visualization techniques across five categories
(1) direct, (2) geometric, (3) texture-based (4) automatic and semi-automatic feature extraction (5) interactive feature extraction
Summary and conclusions
3 Effective Visualization of Heat [email protected]
Cooling Jacket DesignCooling Jacket DesignThree Major
Components of the Geometry:
cylinder head (top) gasket (middle) cylinder block
(bottom)
Pulled apart for illustration only
4 Effective Visualization of Heat [email protected]
The Ideal Cooling Jacket FlowThe Ideal Cooling Jacket FlowTwo major
components to the ideal pattern of flow:
Longitudinal: lengthwise along geometry
1. Transversal: ”up-and-over” direction of the geometry
i.e. shortest path(s) from inlet to outlet
5 Effective Visualization of Heat [email protected]
Cooling Jacket Design GoalsCooling Jacket Design Goalsmajor design goals: transfer heat away from engine
block an even distribution of flow to
each engine cylinder avoid regions of stagnant flow avoid very high velocity flow minimize fluid pressure loss
between inlet and outlet
6 Effective Visualization of Heat [email protected]
Flow Visualization ClassificationFlow Visualization Classification1. direct: overview of vector field, minimal computation, e.g.
glyphs, color mapping
2. texture-based: complete coverage, more computation time, implementation time, e.g., Spot Noise, LIC, ISA
3. geometric: a discrete object(s) whose geometry reflects flow characteristics, e.g. streamlines
4. feature-based: both automatic and interactive feature-based techniques, e.g. flow topology
7 Effective Visualization of Heat [email protected]
Applying Visualization Techniques Across Multiple Applying Visualization Techniques Across Multiple Classifications and ComparingClassifications and Comparing
direct texture-based geometric
feature-based: automatic feature-based: interactive
approaches from all five categories are systematically applied to same application.
8 Effective Visualization of Heat [email protected]
High Temperature and Direct Flow VisualizationHigh Temperature and Direct Flow Visualization
Observations about visualization:
Remarks about cooling jacket application:
Tedious and error prone searching
Limited to surface (or slices)
Can help to visualize areas of high temperature
Can give initial overview
9 Effective Visualization of Heat [email protected]
Identifying Recirculation with Texture-Based Flow Identifying Recirculation with Texture-Based Flow VisualizationVisualization
Recirculation zones are less effective in transferring heat away
one goal is to minimize recirculation zones
Useful because of fast overview and coverage
perceptual challenges due to complexity
10 Effective Visualization of Heat [email protected]
Identifying Recirculation with Texture-Based Flow Identifying Recirculation with Texture-Based Flow VisualizationVisualization
• Cylinder heads receive extra attention
• Bridge between exhaust side ports is critical
Appears not to be a problem here
But, manual inspection and must still look within volume
(color is mapped to velocity magnitude)
11 Effective Visualization of Heat [email protected]
Visualizing Flow Distribution with Geometric Visualizing Flow Distribution with Geometric Approaches (Streamlines)Approaches (Streamlines)
Engineers try to maintain an even distribution of flow to each cylinder
Realized through placement, number, and size of gasket holes
Interactive seeding is tedious
not actually easy to see distribution, but pressure drop is evident
(streamline color mapped to pressure)
12 Effective Visualization of Heat [email protected]
Visualizing Flow Distribution with Geometric Visualizing Flow Distribution with Geometric Approaches (Particles)Approaches (Particles)
Too many streamlines create perceptual problems (too much complexity)
Automatic Seeding is applied at inlet
Avoid perceptual problems, leaving no trails behind
slow/stagnant flow is easy to see
may miss recirculation zones (particles color-mapped
according to velocity magnitude)
13 Effective Visualization of Heat [email protected]
Visualizing Flow Distribution with Geometric Visualizing Flow Distribution with Geometric Approaches (Streamsurfaces)Approaches (Streamsurfaces)
Laminar flow characteristics in cylinder block are evident
laminar flow is broken up at gasket, resulting in very complex structure
14 Effective Visualization of Heat [email protected]
Visualizing Flow Distribution with Geometric Visualizing Flow Distribution with Geometric Approaches (Streamsurfaces)Approaches (Streamsurfaces)
Laminar flow characteristics in cylinder block are evident
laminar flow is broken up at gasket, resulting in very complex structure
Seeding: still a problem Visual complexity: still a
problem
15 Effective Visualization of Heat [email protected]
Extracting Singularities with (Semi-)Automatic Feature-Extracting Singularities with (Semi-)Automatic Feature-Extraction (Cutting Plane Topology)Extraction (Cutting Plane Topology) Vortices have both beneficial
(mixing of cool + hot fluid) and non-beneficial properties (increased resistance in ideal flow directions)
Many vortices present
Visual complexity: still a problem
Cutting plane topology appropriate given a priori knowledge
16 Effective Visualization of Heat [email protected]
Automatic Vortex Core Line Extraction (Sujudi-Haimes)Automatic Vortex Core Line Extraction (Sujudi-Haimes)
Cutting plane technique does not detect all vortices
Sujudi-Haimes vortex core line extraction method was also applied
Visual complexity: less but still a problem
Not necessarily what the engineer is interested in
17 Effective Visualization of Heat [email protected]
Interactive Feature ExtractionInteractive Feature Extraction
A relatively new flow visualization classification
User specifies a region of interest in an information visualization view, e.g., a scatter plot
corresponding geometry is then shown in Focus+Context style visualization.
Smooth brushing is appropriate for CFD simulation data
Engineers may extract a more semantically oriented result.
18 Effective Visualization of Heat [email protected]
Interactive Feature Extraction: Extracting Regions of Interactive Feature Extraction: Extracting Regions of Stagnant FlowStagnant Flow
Regions of stagnant flow are the least effective for heat transfer
Can even lead to boiling conditions: ultimately a shorter product life span
Regions of stagnant flow are shown in magenta
Context is grey-shaded color is mapped to
temperature (blue- highest)
19 Effective Visualization of Heat [email protected]
Interactive Feature Extraction: Extracting Regions of Interactive Feature Extraction: Extracting Regions of Stagnant Flow + High TemperatureStagnant Flow + High Temperature
Stagnant flow + high temperature is a bad combination
Multi-attribute brushing can extract these regions
Very little of the volume corresponds to this selection
Design is rather good from this perspective
(v<0.1 m/s) AND (365K < t)
20 Effective Visualization of Heat [email protected]
Interactive Feature Extraction: Extracting Reverse-Interactive Feature Extraction: Extracting Reverse-Longitudinal FlowLongitudinal Flow
Ideal pattern of flow has both longitudinal and transversal directions
Regions of backward flow are to be avoided
Very little of the volume corresponds to this selection
Design is rather good from this perspective
21 Effective Visualization of Heat [email protected]
Interactive Feature Extraction: Extracting High Interactive Feature Extraction: Extracting High Pressure GradientPressure Gradient
Ideal cooling jacket design minimizes pressure drop between inlet and outlet
Regions of high pressure drop are sub-optimal
Gasket holes are high-pressure gradient regions
Design is sub-optimal from this perspective
22 Effective Visualization of Heat [email protected]
Summary and ConclusionsSummary and Conclusions We applied a feature-rich spectrum of visualization techniques to
analyze flow through a cooling jacket: direct, texture-based, geometric, automatic feature-extraction, interactive feature-extraction
2D slices were generally absent Complex geometry makes parameterization unattractive Texture-based visualization useful because it’s fast and provides
overview Simple particle visualization appealing for perceptual reasons Automatic feature extraction useful, but still limited Interactive feature extraction advantageous in this application due
to arbitrary levels of abstraction
23 Effective Visualization of Heat [email protected]
AcknowledgementsAcknowledgements
Thank you for your attention! Questions?
Thanks To:
Christoph Garth 2
Helmut Doleisch 1
Jürgen Schneider 3
Helwig Hauser 1
Hans Hagen 2
1 The VRVis Reseach Center, Austria
2 University of Kaiserslautern, Germany
3 AVL-AST, Austria
CFD simulation data courtesy of AVL. For more information please visit:
http://cs.swan.ac.uk/~csbob/
24 Effective Visualization of Heat [email protected]
What about Unsteady Flow?What about Unsteady Flow?
Thank you for the excellent question!
Engineers are mostly interested in steady state simulation results, for the case of a cooling jacket
The ideal cooling jacket should quickly reach the conditions under which it stabilizes
25 Effective Visualization of Heat [email protected]
What about Perceptual Problems with Texture-Based Flow What about Perceptual Problems with Texture-Based Flow Visualization?Visualization?
This is a super good question!
Image overlay opacity is arbitrary and thus user-controlled!