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Old 04-01-2014, 01:48 PM   #1
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I guess this would be a physics question...

So I fill the large dog bowl on the deck with a hose. With the hose fully on, if I touch the bottom of the bowl with the hose end, it is attracted or sticks to the bottom.

How does that work???
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Old 04-01-2014, 02:06 PM   #2
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I believe you are referring to an aspiration effect, similar to quick deploy air filled devices (aircraft emergency slides, life raft, etc). The water rushing out is pulling the surrounding water with it, creating an area of low pressure. The weight (pressure) of the water outside this zone is greater than within it.

If the bottom of the bowl is curved, could be a reverse lift effect, similar to an airfoil or hydrofoil.
Sound right?

Last edited by particlewave; 04-01-2014 at 02:11 PM.
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Old 04-01-2014, 02:33 PM   #3
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Yes, Bernoulli effect.

Similar effect to blowing across the top of a sheet of paper, high speed flow creates low pressure which pulls the paper up towards the higher speed air.

or ping pong ball suspended in midair in blower air stream. Higher speed air keeps ball in center of air stream as thats where the lower pressure is.

or aircraft wing (Spoiler), lower curved surface makes the airflow accelerate and hence creates lift in the down direction on the lower side towards the faster moving air stream.

or car air dam that forces the air through a smaller gap between air dam and road causing airflow to speed up and that is what creates the suction that helps keep the car in contact with the road.
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Old 04-01-2014, 02:33 PM   #4
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When a given volume of fluid moves through a restriction, it speeds up and the pressure drops (Bournelli effect). The "attaction" is really the higher outside pressure pushing against the lower presure in the faster moving fluid squirting through the gap between the hose and the bowl. This principle is what make carburetors work. It can also be demonstrated by taking a 3x5 card, a pin, and a spool of thread. Poke the pin through the middle of the card, inset the pin into the hole at one end of the spool, then blow through the other end of the spool. The card sticks to the spool because the air speeds up between the face of the spool and the card. The more air that goes through the spool, the harder the card sticks.
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Old 04-01-2014, 07:21 PM   #5
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This forum is still the best!
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Old 04-01-2014, 08:56 PM   #6
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Whip! How's it going buddy?
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Old 04-02-2014, 05:22 AM   #7
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Quote:
Originally Posted by particlewave View Post
Whip! How's it going buddy?
Hey man! Well I've been hanging out on the other forum where they all have new 981s. Having sold both my 986 and 987 I'm not doing much machanical stuff now a days. The highlight of my 981 is a pulled an air filter for the fun of it and changed the oil. I come over to 986forum when I need a little brain stimulation.
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