A pres

1. Examining
Bernoulli’s
Principle
through the
McKee Breezeway
Measuring the Effects of Building Construction on Wind Flow
Through a Structure
Ross Kononen, Keri Bowling, Nick Horianopoulos, and Matt Nolen

2. Scientific Observation
• McKee Hall’s breezeway
– Uncomfortable!
– Cold
– Windy

3. Scientific Observation
- Ross Kononen noticed wind while
skateboarding

4. Scientific Question
• Why does the wind velocity appear to
increase inside of the McKee breezeway?
• Probable Cause: Dynamic of wind changed by
some property of building

5. Hypothesis
• If the McKee Hall Breezeway acts as a venturi,
then:
1. High pressure will exist in front of
and behind the breezeway
2. Low pressure will exist within the
breezeway
3. The velocity within the breezeway
will increase due to the pressure
differential between the outside
and the inside of the breezeway

6. Supporting Literature
• Blocken B, Stathopoulos T, Carmeliet J. (2008) Wind environmental
conditions in passages between two long narrow perpendicular buildings.
Journal of Aerospace Engineering – ASCE 21(4): 280-287
• Gaimbattista, A., Richardson, B., & Richardson, R.C. (2010) Physics (2nd ed.).
New York, NY: McGraw-Hill Companies, Inc.
• Heim, D., and Klemm, K., (2009) LOCAL WIND AND RAIN CONDITIONS IN
SEMI-CLOSED NARROW CORRIDORS BETWEEN BUILDINGS , Eleventh
International IBPSA Conference, Glasgow, Scotland July 27-30, 2009 1745 –
1752.
• McIlveen, J. F. R., (2002) The everyday effects of wind drag on people,
Weather , Vol. 57, pp. 410-417
• Serway, R.A., Faughn, J.S. Vuille, C., Bennett, C.A., (2006) College Physics, (7th
ed.), Belmont, CA: Thomas Brooks/Cole, Ch. 6, 160-164
• APB Foundation. (1998). Session 9, Part B: Surface Area and Volume. Retrieved
November 04, 2011, from Learning Math: Measurement:
http://www.learner.org/courses/learningmath/measurement/session9/solution
s_b.html#b8

7. Examination of Space

8. Examination of Space
We thought we
Initial Speed 2.995 m/s
could model a value
Final Velocity 0. 939 m/s
for the wind slowing
Ross down
Outside headwind 2.995 m/s
Inside headwind???
8.3m from motion equations
Ignored:
•Friction (ground, wheels, Ross’ hair)
•Rotational losses
•Vectors
4.25s an estimate

9. Estimation of Wind Speed
Used momentum equation to determine force required to slow Ross down:
F t p mV f mVi
m m m
116.1 kg 2.995 116.1 kg 0.939 238 .7 Kg
s s s
p
Fav
t
m
238.7 Kg
s 56.2N
4.25s

10. Estimation of Wind Speed
Estimation of Drag Force (modeled at 0.50)
2
Cd Av drag force (in N)
2
Where: known from
momentum
equation
Air Density, usually 1.2 kg/m3
Cd Coefficient of Drag, 0.5 (McIlveen 2002)
A Area, m2 1.2
Kg
m3 0.50 0.4247m 2 v 2 56.2N
v Velocity in m/s 2
m m m
v 21.0 original headwind of 2.995 18.01
s s s

11. Estimation of Wind Speed
Estimation of Drag Force (modeled at 0.85)
2
Cd Av drag force (in N)
2
Where: known from
momentum
equation
Air Density, usually 1.2 kg/m3
Cd Coefficient of Drag, 0.85 (Engineering Toolbox, 2011)
A Area, m2 1.2
Kg
m3 0.85 0.4247m 2 v 2 56.2N
v Velocity in m/s 2
m m m
v 16.1 original headwind of 2.995 13.11
s s s

12. Rosstimation
• Ross is 6’4” or 193 cm
• Make a square with arms out
• Fingertip-fingertip distance is
roughly your height
• Square that value, 3/5ths = surface area
(Annenberg Foundation 2011)
19%
•Only 19% surface area exposed to
relative wind
•Side profile 4247cm2 or 0.4247m2

13. Physicist Approved!
• Dr. Matthew Semak
• Numbers and physics “make sense”

14. So to review…
• 13-18 m/s (46 kph to 65 kph) gusts slowing a
skateboarder in 8m and 4 ¼ seconds inside
McKee Breezeway
• We should expect values somewhat close to
these if hypothesis = valid (a 1:~7 down to a 1:4 ratio
of speed inside to speed outside)
• We began our research!

15. Data Collection
• We collected data…

16. Data Collection
• Three data collectors
• Data taken:
– 10 readings
– 30 seconds
– 5 minutes total

17. Data Collection
Equidistant, along centerline

18. Data Collection
• We used calibrated anemometers
• Precision to the 1/10th m/s

19. Collection Problem
• Notes
– Surprisingly few windy days
• 10 attempts, 3 conditions of observable data

20. Collection Problem
• Unique weather conditions
– When in Colorado is it not windy during Fall?
– Four years history – winds low in 2011!
• Wind mostly came from out of NNE
– Also unusual
• Last reading came out of SSW!
– Low wind readings outboard
– High wind readings inside
– Supporting?

21. Collection Problem
October 2011
October 2010

22. Findings
Observations on Oct. 20, 2011
14 Observations on Nov. 6, 2011
Wind Velocity (km/h)
12 8
10 7
Wind Velocity (km/h)
8 6
6 5
4 4
2 3
0 2
1
1 2 3 4 5 6 7 8 9 10
0
Trial Number
1 2 3 4 5 6 7 8 9 10
Trial Number
Observations on Oct. 25, 2011
12
SE Side of McKee
10
Wind Velocity (km/h)
Breezeway Center
8 NW Side of McKee
6
4
2
0
1 2 3 4 Trial 5 6
Number 7 8 9 10

23. Findings
Average Wind Velocities from Measurement Points
9
Average Wind Velocity (km/h)
8
7
Oct.
6 20
5
Oct.
4
25
3
2 Nov.
06
1
0
SE side Breezeway NW side
Measurement Point
Mostly shows higher wind values
outside of breezeway than inside!
AHHHHHH!

24. Findings
Do we reject hypothesis?
•Majority of observations do not support
hypothesis
•Curious conditions cause suspicion
•Not enough data able to be taken to support
conclusion either way
•Why??

25. Analysis
•What we think
happened:
High pressure
(low speed)

26. Potential Sources of Error
• Trees
• Measurement error
– Face into wind?
• Oddball weather conditions
October 2011
October 2010

27. Applying this to classroom
•Teach learners that science is complex
•Object lesson: wind patterns, historical data
•You may have to make many observations to
prove or disprove hypothesis
•Inquiry based projects promote group work
skills
•You may not just get different results, you may
get results that don’t match observations
•Knowledge of Bernoulli’s Principle can help
students make better decisions during the
course of their lives