Flow Visualization

CS 4390/5390 Data Visualization

Shirley Moore, Instructor

November 24, 2014

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Announcements

• Tests will be graded by next Monday, can do retake finals week if needed

• Project design documents are due today. Turn in tomorrow (Tuesday) by midnight in order not to lose points (turn in hard copy or email to svmoore@utep.edu)

• Final exam period is Friday, December 12, 1:00-3:45pm; Final projects are due then.

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Understanding Fluid Flows

• Dynamics causing the flow (forces)– Pressure, buoyancy, inertia, viscous

forces, surface forces…. Etc.

• Effects of these forces on the flow (Flow and fluid properties)– Velocity, acceleration, vorticity– Viscosity, temperature, scalar

concentration, density …. Etc.

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Why Flow Visualization

• Understand flow phenomena• Verify model or theory results• Easier measurements• To get a priori knowledge of a

solution

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What we need to visualize

• Stream lines– a line, tangent to which at any given instant

is the velocity vector at that point

• Streak lines– locus of particles which have passed through

a prescribed point during a specified time interval

• Path lines– locus of points traversed by a given fluid

particle during some specified time interval

• Time lines– line joining different adjacent points at any

instant of time5

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Flow visualizationLeonardo Da Vinci’s Hand drawings

Naturally occurring flow visualization

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Flow Past a Cylinder

Clouds past a mountain

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Methods of flow measurement

• Gas flows– Smoke visualization– Particle– Shadowgraphs and Schlieren

• Liquid flows– Dye– Shadowgraphs and Schlieren– Particles– Bubbles– Fluorescence, phosphorescence

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Some gas flow visualization images

Smoke visualization

Top- flow past aerofoilSide- laminar smoke jet

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Schlieren flow visualizationShadowgraph

Bullet at supersonic speed

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Flow over AerofoilSide –particle visualizationBelow –dye visualization

Liquid flows

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Insects walking on water

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Drop falling on liquid surface

Normal laminar flow chain14

Jets and Plumes

•Top left- flow below an ice cube in water

•Top right- near field of a jet

•Side- jet and flame jet

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Buoyant jet in stratified fluid

Tear ducts in wine glass

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Computational Fluid Dynamics

• Simulates fluid flow by solving differential equations using numerical methods

• CFD has taken the place of wind tunnels for many evaluations of aircraft and, as computing power increases and computer models become more sophisticated, CFD will largely replace wind tunnels.

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Streamlines, Pathlines, and Streaklines

• Streamlines– https://www.youtube.com/watch?v=TOUylg7Eyec  

• Pathlines– https://www.youtube.com/watch?v=ZRUYHQCQLBk

•  Streaklines– https://www.youtube.com/watch?v=UqHd3pnEKtA

• Popular streamline, pathline, streakline videos– https://www.youtube.com/playlist?

list=PLvQKTRyZQ7uKIUcYY2bnQh0Hqx2lVDAub

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Pathlines in Paraview

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Flow Visualization Examples

• NASA– http://www.grc.nasa.gov/WWW/k-12/airplane/tunvis.html

• Flometrics– http://www.flometrics.com/fluid-dynamics.shtml

• Flow visualization course at University of Colorado– http://www.colorado.edu/MCEN/flowvis/galleries/

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For Next Class

• Finish Quiz 5, turn in for grade

• Work on Lab 5

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