1. IYPT 2010 Austria, I.R. Iran Reporter: S.M. Bousaki 1

2. IYPT 2010 Austria, I.R. Iran The question A transparent vessel is filled with a liquid (e.g. water). A jet flows out of the vessel. A light source is placed so that a horizontal beam enters the liquid jet (see picture). Under what conditions does the jet operate like a light guide? 2

3. IYPT 2010 Austria, I.R. Iran Contents Basic understanding Hydraulic studies –Theory –Experiments –Head loss calculation –Comparison Optical studies –Theoretical calculation –Experiments –Comparison Conclusion 3

4. IYPT 2010 Austria, I.R. Iran Basic understanding Light guide definition Refraction and total reflection 4 So… the shape of the liq jet is really important 4 us because we can find the angle … Hydraulic investigation Optical investigation s.Th that guides light throw it shape

5. IYPT 2010 Austria, I.R. Iran Hydraulic studies Finding the path using liquid projectile motion. That v is the velocity of the liquid particle. 5

6. IYPT 2010 Austria, I.R. Iran Hydraulic studies Finding the velocity using Bernoulli equation & head loss formula Darcy–Weisbach equation: That c in it is the head loss coefficient. 6 says that the head loss is proportional with that we can concluding that:

7. IYPT 2010 Austria, I.R. Iran Hydraulic studies - Experiments Setup –3 holes –High vessel –Pump 7

8. IYPT 2010 Austria, I.R. Iran 8 Hydraulic studies - Experiments Finding the liquid path,use picture analyzing

9. IYPT 2010 Austria, I.R. Iran Hydraulic studies - Experiments The liquid paths are parabola 9

10. IYPT 2010 Austria, I.R. Iran Hydraulic studies - Experiments Finding the head loss So the slope between real head and theory head equals to “1+c” 10

11. IYPT 2010 Austria, I.R. Iran Hydraulic studies - Experiments Comparison –The linear relation between the real head and the hydraulic head shows the mach between theory and experiments. 11

12. IYPT 2010 Austria, I.R. Iran Optical Studies Reasoning that the first reflection is enough –Curvature radii According to the shape… –Thickness Discharge conservation => Inverse relation with velocity *

13. IYPT 2010 Austria, I.R. Iran Optical studies Using the jet path to find the first attachment angle 12

14. IYPT 2010 Austria, I.R. Iran Optical studies Comparing with critical angle The jet acts as a light guide if 13

15. IYPT 2010 Austria, I.R. Iran Semi guidance situation 14 Optical Studies

16. IYPT 2010 Austria, I.R. Iran 15 Optical Studies

17. IYPT 2010 Austria, I.R. Iran Guidance-velocity head graph 16 Optical Studies

18. IYPT 2010 Austria, I.R. Iran Optical studies - Experiments Setup –Wide light source –Black vessel side 17

19. IYPT 2010 Austria, I.R. Iran Measurement –Using a camera to measure the intensity and the energy. 18 Optical studies - Experiments

20. IYPT 2010 Austria, I.R. Iran Camera calibration –Finding the relation between RGB and intensity 19 Optical studies - Experiments 25cm 30cm 31cm 40cm50cm

21. IYPT 2010 Austria, I.R. Iran Camera calibration 20 Optical studies - Experiments

22. IYPT 2010 Austria, I.R. Iran Analyzing pictures with MATLAB program 21 Optical studies - Experiments

23. IYPT 2010 Austria, I.R. Iran 22 Optical studies - Experiments guidance Velocity head(cm)

24. IYPT 2010 Austria, I.R. Iran 23 Optical studies – Exp & theory comparison guidance Velocity head(cm)

25. IYPT 2010 Austria, I.R. Iran Conclusion The liquid path is parabola, as we calculated. Our theory was true about the reason of the phenomenon. Light guide condition is the case where the hydraulic head would be more than: 24

26. IYPT 2010 Austria, I.R. IranIYPT 2010 Austria, National team of I. R. Iran