Can Strong Winds Cause High Building Windows to Open Outward?

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Homework Help Overview

The discussion revolves around the effects of strong winds on high-rise building windows, specifically whether the pressure difference created by wind can cause windows to open outward instead of inward. The problem involves concepts from fluid dynamics, particularly Bernoulli's equation and pressure differentials.

Discussion Character

  • Exploratory, Conceptual clarification, Assumption checking

Approaches and Questions Raised

  • Participants explore the application of Bernoulli's equation to analyze pressure differences inside and outside the building. Questions arise regarding the assumptions made about static and dynamic pressures, as well as the conditions under which Bernoulli's principle can be applied. Some participants express uncertainty about the effects of turbulence and the flexing of window panels.

Discussion Status

The discussion is active, with participants questioning the validity of applying Bernoulli's principle in this context. Some suggest that external factors like turbulence and the physical properties of the windows may influence the outcome. There is no explicit consensus, but various interpretations and considerations are being explored.

Contextual Notes

Participants note the complexity of the situation, including the interaction of static and dynamic pressures, and the potential for window flexing under wind pressure. There is mention of a specific exercise in a physics textbook that relates to the problem, indicating a shared reference point for discussion.

Gyroscope

Homework Statement


This is one more problem I made to entertain myself.

I am at the highest floor of a building near a window. There is strong wind outside.
The pressure inside is approximately the atmospheric pressure, but outside it is less because the air is flowing, so by Bernoulli's equation it must be at a lower pressure.
Therefore, there is a difference in pressure between the outside and the inside, which creates an outward net force on the window, so will it open outward and not inward as intuition states. Is this right?
 
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Why would the pressure be less on the outside of the window? There are two components to the external pressure in this case, the static atmospheric pressure and the dynamic pressure caused by the wind. The static is opposed from the inside, but not the dynamic. Do you have an eqn for dynamic pressure?
John
 
Applying Bernoulli to points A (outside) and B(inside):

P_A + 1/2ρv^2=P_B

But P_B=P_atm. So:

P_A=P_atm - 1/2ρv^2, ρ is the density of air.

So the windows should pop out. Right?
 
I don't think this is a proper use of Bernoulli's since the two systems are not in contact.

The force of the outside is represented correctly however as is the sum of the dynamic and static pressures, as is the inside. so Pa-Pb=1/2Pv^2, ie from substitution and the following,


Pa=atm plus 1/2Pv^2
pb=atm
 
If you actually go in a tall building you can watch the large glass window panels flex both in and out.
So the direction would depend on the flex state at the point of failure.
I would think turbulence plays a major role here.

Since I've seen an example of one failing, I stay away from them when they start to get major deflections.
 
NoTime said:
If you actually go in a tall building you can watch the large glass window panels flex both in and out.
So the direction would depend on the flex state at the point of failure.
I would think turbulence plays a major role here.

Since I've seen an example of one failing, I stay away from them when they start to get major deflections.

No doubt, but I don't think this is what Gyro's ? was about. I was assuming a constant wind perpendicular to the window which should bend it it, now gusting, aerodynamic flutter, the elasticity of the mount, and mother nature might well conspire to cause it to break out.
 
So, i can't apply Bernoulli's to this situation?
 
It happens that I found an exercise in Physics for scientists and engineers by Serway, which is exactly similar to this, and they apply Bernoulli to points outside and inside the building. I do not know what to believe :S , maybe I need to make some experiments. :)
 
  • #10
No I think I might have misled you in some respects because I'm used to seeing it used mostly in the context of a contiuous stream. If you scroll down about 2/3'rds the page I linked, you will see the solution for stagnation pressure which applies here.
 

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