foamvis: visualization of 2d foam simulation data

VisWeek 2011 - Providence, RI, USA 1

FoamVis: Visualization of 2D Foam Simulation Data

Dan R. Lipşa1, Robert S. Laramee1, Simon J. Cox2,and I. Tudur Davies2

1The Visual and InteractiveComputing Group

Computer Science Dept.Swansea University

Swansea, Wales, UK

2Institute of Mathematics and Physics

Aberystwyth UniversityAberystwyth, Wales, UK

27 October 2011

Dan R. Lipsa – Swansea [email protected]


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Overview

Motivation and Introduction to Foam Research

FoamVis Features Results Summary and

Conclusions Visualization of bubble paths color-mapped to elongation.



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Motivation: Why Study Foam?

Displaces oil from porous media Mineral flotation and separation



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Foam

Two-phase material: liquid and gas Complex behavior:

Elastic solid at low stress Plastic solid as stress increases Liquid at high stress



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Foam Research Main Challenge

Foam behavior - Herschel Bulkley:

Plastic solid

Liquid

Foam properties:- bubble size- bubble distribution- liquid fraction- surface tension?

Possible solution:Simulate foam at bubble scale (Surface Evolver)



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Foam Simulations Constriction

704 bubbles 1000 time steps

Sedimenting discs 1500 bubbles 252 time steps



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Topological Change Bubbles in a 2D foam at

equilibrium are 3-way connected at 120º angles.

As foam is sheared, the topology of the soap film changes.

Topological changeBubbles color-mapped by velocity magnitude.

Constriction simulation.



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Motivation: Bubble Scale Simulation Research Challenges

Triggers to various foam behaviors are difficult to infer. Multiple attributes

Difficult to visualize general foam behavior. Time-dependent Large fluctuations in attribute values caused by

changes in the topology of the film network.



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Motivation: Standard Methods for Foam Visualization Drawbacks

Require intervention in the simulation code for summarizing and saving the relevant data.

No ability to explore and analyze data through navigation, selection and encoding.

Slow, coarse level of detail.

Constriction simulation, Average velocity over all time steps



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FoamVis Features Works with any Surface Evolver (SE) simulation: parse

and process directly SE files Color mapping of bubble attributes: velocity, pressure,

area, deformation Overlays

Topological changes Forces

Constriction simulation, Average velocity over all time steps



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FoamVis Features Bubble selection/filtering: by bubble ID, location, and

attribute value (using a histogram) Image based statistical computation (average, count)

For all time steps or for a time window behind the current time step.

Around a moving body Bubble paths Multiple linked views Focus&Context

Bubble and viewWhere do most bubbles with negative velocity along X occur? Count + Topological changes overlay.



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Results: Pattern of Bubble Centers Traversing Loops

Sedimenting discs simulation. Pattern of bubbles traversing loops. Orange: descent, Purple: ascent



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Results: Why Do Bubbles Traverse Loops?

Why do bubbles traverse loops?



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Results: Why does one disc descend quicker than the other?

Sedimenting discs simulation (t=0).Elongation: blue-red palette, Pressure: blue-tan palette.Network force: black, Pressure force: yellow Resultant force: green.

The network force - contacting soap films pull normal to the circumference with the force of surface tension.The pressure force - adjacent bubbles push against the disc with their pressure force.



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Sedimenting-discs simulation (t=43). Elongation - blue-red palette, Pressure - blue-tan palette. Sliding time window average over 10 iterations. Network force: black, Pressure force: yellow Resultant force: green.

Results: Why do discs drift laterally as they sediment?



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Summary and Conclusions Foam research application area. FoamVis - exploration, visualization and analysis of

foam simulation data. Validate hypothesis, make new discoveries and gain

insight into foam behavior.



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Acknowledgments We thank Ken Brakke, Susquehanna University, PA, for

answering our many questions about the Surface Evolver. This research was supported in part by:

EPSRC/P&G grant EP/F000049/1, EPSRC grant EP/D071127/1 Research Institute of Visual Computing (rivic.org) Wales

Thank you for your attention! Any questions?



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Why 2D foam simulations?

Shorter simulation time. Available 2D experimental data. Experimental data easier to segment.

Image by E. Janiaud



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Surface Evolver Foam simulation program - Ken Brakke, Mathematics

Department, Susquehanna University, PA Study of surfaces shaped by surface tension and other

energies, and subject to various constraints

Input Output

Soap film with fixed (square wire frame) and free boundaries (surface of the table)

foamvis: visualization of 2d foam simulation data

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