🧵 on the Coanda Effect....
Highlights
- 🧵 on the Coanda effect. 1/ As stated before, the eccentric MR jet hugging the atrial wall is not due to the Coanda effect. As the jet is directed towards the wall, it is deflected, as it has to follow the wall, having nowhere else to go.
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- 2/ The Coanda effect is related to the Bernoulli principle of conservation of energy. A high velocity jet (of gas in gas or fluid in fluid), will recruit surrounding medium which accelerates. As velocity (kinetic energy) increases, pressure (potential energy) must drop.
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- 3/ The higher ambient pressure, will push air in towards the jet, due to the negative pressure gradient.
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- 4/ If there is a solid wall on one side of the jet (whether straight or curved, the pressure will drop on both sides of the wall, but the ambient pressure will push the jet towards the wall, even if it inclines away from the jet. This apparent paradox is the Coanda effect
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- 5/ A jet directed towards a surface inclining into the jet, will hit the wall, and then be deflected to follow the wall. This is purely mechanical, and there will be pressure buildup from the jet velocity along the wall, obviously the opposite of Coanda.
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- 6/ I'm more uncertain about the water-in-air flowing along the outside of a curved surface. Could be mainly the surface tension of waters or with some Coanda effect in addition, but this depends on the relative strength of the two forces. Some say it's Coanda, some say it's not.
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- -so the picture I posted before, was not so certain. My error. Sorry😨 (View Tweet)