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Introduction to Fluid Mechanics

Introduction to Fluid Mechanics. Bellagio Fountain. Lecture 9: Introduction to Fluid Mechanics Approximate Running Time - 33 minutes Distance Learning / Online Instructional Presentation Presented by Department of Mechanical Engineering Baylor University Procedures:

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Introduction to Fluid Mechanics

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  1. Introduction to Fluid Mechanics Bellagio Fountain

  2. Lecture 9: • Introduction to Fluid Mechanics • Approximate Running Time - 33 minutes • Distance Learning / Online Instructional Presentation • Presented by • Department of Mechanical Engineering • Baylor University • Procedures: • Select “Slide Show” with the menu: Slide Show|View Show (F5 key), and hit “Enter” • You will hear “CHIMES” at the completion of the audio portion of each slide; hit the “Enter” key, or the “Page Down” key, or “Left Click” • You may exit the slide show at any time with the “Esc” key; and you may select and replay any slide, by navigating with the “Page Up/Down” keys, and then hitting “Shift+F5”.

  3. Introduction Dr. Carolyn Skurla Speaking

  4. Aerodynamics Forces On An Airplane • What causes drag and lift? ldaps.ivv.nasa.gov/physics/lift.html

  5. Drag • Drag is a function of friction • F = drag force • CD = drag coefficient •  = density of the fluid • A = characteristic area • depends on body shape • v = free-stream velocity

  6. Characteristic Area • The shape of the silhouette of the object • If you were a molecule of water flowing toward the object • And there was a light behind the object • What would the object look like to you?

  7. L d Characteristic Area • Cylinder with fluid flow perpendicular to length of cylinder?

  8. L Characteristic Area • Cylinder with fluid flow parallel to length of cylinder? d

  9. Example Problem: Drag L r

  10. Example Problem: Drag L r

  11. Drag On A Cylinder - Why? No Flow Separation Stagnation Point Stagnation Point

  12. Friction, that’s why! Drag On A Cylinder

  13. Which Has More Drag?

  14. Better streamlining of cars over the years Lower drag force & better fuel efficiency! Why Do We Care About Drag?

  15. Example Of Friction http://www.dfrc.nasa.gov/gallery/photo/SR-71/

  16. Example Of Friction

  17. Fluid Exerts a Force • Drag -> Acts in the direction opposite to the motion of the object. • Lift -> Acts at right angles to the drag. (http://www.titleist.com/technology/aerodynamics.asp)

  18. Example of Lift • Lift caused by pressure differential between top and bottom of wing. ldaps.ivv.nasa.gov/physics/lift.html

  19. How Does a Curveball Work? • A spinning ball curves in flight • Magnus effect • Stitches are NOT required to make a baseball curve http://popularmechanics.com/science/sports/1997/4/breaking_pitch/print.phtml

  20. Lift On A Golf Ball • How does a golf ball generate lift? (www.titleist.com/htm/tech/aero_main.asp)

  21. Why are Golf Balls Dimpled? Dimples No Dimples (www.titleist.com/htm/tech/aero_main.asp)

  22. Drag Force on Dimpled vs. Smooth Golf Balls • Dimpled golf balls generate less drag! • Increases angle of separation for transition to turbulence. (www.titleist.com/htm/tech/aero_main.asp)

  23. Lift Force on Dimpled vs. Smooth Golf Balls • Backspin generates lift! • Dimpled golf balls have slightly improved lift. (www.titleist.com/htm/tech/aero_main.asp)

  24. This Concludes Lecture 9

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