CoandaEffect

康達效應

Category:

Howto & Style

Tags:

• coanda
• effect
• 康達效應

[crazydandan]

excellent demonstration, we appreciate your contribution

[kiscky]

on airplanes' wings to make them fly!! =)

[kazioo2]

@yutewang

"A common misconception is that Coandă effect is demonstrated when a stream of tap water flows over the back of a spoon held lightly in the stream and the spoon is pulled into the stream. While the flow looks very similar to the air flow over the ping pong ball above (if one could see the air flow), the cause is not really the Coandă effect. This particular demonstration is dominated by surface tension." - wikipedia.

[Sylvanian1000]

Really great idea, excellent demonstration.

[cashmab]

Excellent, demonstrative experiment!

[sigung01]

Wow, never thought of that, thank you for your insightful comment.

[cashmab]

There is still debate as to which better describes the principles of flight, but most aerodynamicists believe that the Coanda effect describes lift of an airplane wing to a greater degree than the Bernoulli principle. Really, both principles are different ways of describing essentially the same net result --Newton's laws of motion (e.g., F=ma), but one better describes the aerodynamic than the other.

[cashmab]

The horizontal component of that diverted flow vector is what holds the spoon in the stream of water.

[cashmab]

No, this effect is not adequately described by the Bernoulli principle. The viscosity of the fluid (air in the case of an airplane wing, or tap water in the above experiment) causes the fluid to adhere to the curved surface due to a gradient in friction (highest friction at the surface of the spoon) and directs the flow beyond the trailing edge at whatever trajectory it departed the trailing edge from. The result is a fluid flow departing the spoon at a greater angle than vertical.

[NYFlyer1]

You can also see the different flow regimes for the water coming out of the spigot. The flow seems to be first laminar, and then with the increased flow rate, the water enters the transition regime and the finally the fully turbulent regime. Overall, very good experiment!

[vanepico]

Cool experiment!!!

[PerfectBlindness]

thanks, I couldn't tell from the video. That's a real help. :D