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Air Flow in My Room

  1. Jun 23, 2017 #1
    Hi, I have a question about air flow. My room is located on the corner-end of my building, on the 7th floor. I have two windows, each one facing a different side of the building, and one of the windows typically produces the breeze, and the other never does.

    When the door to my room is closed, there is typically less of a breeze. When the door is open, the breeze picks up a little. This is all fine and good, but here's where it gets interesting:

    The closer the door is to being completely shut. the more the breeze intensifies. It's like the air outside is rushing through my room to get into the rest of my house before the door closes. I can feel the resistance the door exerts on me, and it gets stronger the closer the door is to being completely shut.

    Whenever I feel too hot, I can summon a strong refreshing blast of wind by just pushing the door towards the doorframe till it's open just a crack. And here's the thing, if the door does shut completely, the wind stops immediately.

    Can someone please explain what exactly is going on?
     
  2. jcsd
  3. Jun 23, 2017 #2

    Borek

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    Staff: Mentor

    If the volumetric flow of air is more or less constant, air has to flow faster through a smaller opening, nothing unusual here.
     
  4. Jun 23, 2017 #3
    So is my room actually "pulling" more air from outside? Or is it the same amount of air from my room merely travelling faster through the opening in the doorway?

    I'm also unsure as to why the air flows faster simply because there is a smaller opening. What compels the air to move faster? Why doesn't it just travel at the same speed through the smaller opening?
     
  5. Jun 23, 2017 #4
    I know that water travelling through a pipe moves faster if the pipe narrows, but isn't that because the system is enclosed? That is, there are no other openings in the pipe besides the hole the water went in through and the hole it comes out of. The water is moving straight A to B.

    I figure my house isn't a closed system, from my room to the rest of the house there's just the one doorway, but beyond that there are several different hallways and rooms with open windows in all directions. So why is the compelled to travel faster through the smaller opening if there isn't a straight A to B line?

    Or is all of that irrelevant? My room is A and the other side of the doorway is B? Or am I completely wrong here?
     
  6. Jun 23, 2017 #5

    russ_watters

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    Staff: Mentor

    The building "wants" a certain amount of airflow, so the volumetric flow through the door doesn't drop much until the door is nearly closed. I bet if you stood by the window instead of the door, you would notice very little change until the door was almost closed, then it would start to drop.
     
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