1. © 2006 Baylor University Slide 1 Introduction to Fluid Mechanics Bellagio Fountain

2. © 2006 Baylor University Slide 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: 1.Select “Slide Show” with the menu: Slide Show|View Show (F5 key), and hit “Enter” 2.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” 3.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. © 2006 Baylor University Slide 3 Introduction Dr. Carolyn Skurla Speaking

4. © 2006 Baylor University Slide 4 Aerodynamics Forces On An Airplane What causes drag and lift? ldaps.ivv.nasa.gov/physics/lift.html

5. © 2006 Baylor University Slide 5 Drag Drag is a function of friction –F = drag force –C D = drag coefficient –  = density of the fluid –A = characteristic area »depends on body shape –v = free-stream velocity

6. © 2006 Baylor University Slide 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. © 2006 Baylor University Slide 7 Characteristic Area Cylinder with fluid flow perpendicular to length of cylinder? L d

8. © 2006 Baylor University Slide 8 Characteristic Area Cylinder with fluid flow parallel to length of cylinder? L d

9. © 2006 Baylor University Slide 9 Example Problem: Drag r L

10. © 2006 Baylor University Slide 10 Example Problem: Drag r L

11. © 2006 Baylor University Slide 11 Drag On A Cylinder - Why? Stagnation Point No Flow Separation

12. © 2006 Baylor University Slide 12 Drag On A Cylinder Friction, that’s why!

13. © 2006 Baylor University Slide 13 Which Has More Drag?

14. © 2006 Baylor University Slide 14 Why Do We Care About Drag? Better streamlining of cars over the years –Lower drag force & better fuel efficiency!

15. © 2006 Baylor University Slide 15 Example Of Friction http://www.dfrc.nasa.gov/gallery/photo/SR-71/

16. © 2006 Baylor University Slide 16 Example Of Friction

17. © 2006 Baylor University Slide 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. © 2006 Baylor University Slide 18 Example of Lift ldaps.ivv.nasa.gov/physics/lift.html Lift caused by pressure differential between top and bottom of wing.

19. © 2006 Baylor University Slide 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. © 2006 Baylor University Slide 20 Lift On A Golf Ball How does a golf ball generate lift? (www.titleist.com/htm/tech/aero_main.asp)

21. © 2006 Baylor University Slide 21 Why are Golf Balls Dimpled? Dimples No Dimples (www.titleist.com/htm/tech/aero_main.asp)

22. © 2006 Baylor University Slide 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. © 2006 Baylor University Slide 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. © 2006 Baylor University Slide 24 This Concludes Lecture 9