Robert S. Laramee Department of Computer Science University of Wales, Swansea, UK...

Robert S. LarameeDepartment of Computer Science

University of Wales, Swansea, UK

[email protected]

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


Cooling Jacket DesignCooling Jacket DesignThree Major

Components of the Geometry:

cylinder head (top) gasket (middle) cylinder block

(bottom)

Pulled apart for illustration only


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


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


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


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.


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


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


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)


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)


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)


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


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


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


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


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.


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)


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)


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


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


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


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/


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


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!

Robert S. Laramee Department of Computer Science University of Wales, Swansea, UK...

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