Flow Visualization CS 4390/5390 Data Visualization Shirley Moore, Instructor November 24,

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 to Final exam period is Friday, December 12, 1:00-3:45pm; Final projects are due then. 2

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. 3

Why Flow Visualization Understand flow phenomena Verify model or theory results Easier measurements To get a priori knowledge of a solution 4

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 time 5

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Flow visualization Leonardo Da Vinci ’ s Hand drawings Naturally occurring flow visualization 7

Flow Past a Cylinder Clouds past a mountain 8

Methods of flow measurement Gas flows –Smoke visualization –Particle –Shadowgraphs and Schlieren Liquid flows –Dye –Shadowgraphs and Schlieren –Particles –Bubbles –Fluorescence, phosphorescence 9

Some gas flow visualization images Smoke visualization Top- flow past aerofoil Side- laminar smoke jet 10

Schlieren flow visualizationShadowgraph Bullet at supersonic speed 11

Flow over Aerofoil Side –particle visualization Below –dye visualization Liquid flows 12

Insects walking on water 13

Drop falling on liquid surface Normal laminar flow chain 14

Jets and Plumes Top left- flow below an ice cube in water Top right- near field of a jet Side- jet and flame jet 15

Buoyant jet in stratified fluid Tear ducts in wine glass 16

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. 17

Streamlines, Pathlines, and Streaklines Streamlines – Pathlines – Streaklines – Popular streamline, pathline, streakline videos – UcYY2bnQh0Hqx2lVDAubhttps:// UcYY2bnQh0Hqx2lVDAub 18

Pathlines in Paraview 19

Flow Visualization Examples NASA – Flometrics – Flow visualization course at University of Colorado – 20

For Next Class Finish Quiz 5, turn in for grade Work on Lab 5 21