On winter break and was trying to build an RC airplane from scratch. I was so confused while learning aerodynamics on why air would follow a wing. This summed it up perfectly, than you Harvard!
it's the cause of low pressure over a wing.. but the wing requires forward motion... this effect create vertical lift on a bowl or saucer shape or a sphere, as we just saw.. it still takes work to move mass.. so... the air has to be really moving.. or the sphere really light.. like a soap bubble;;☆》.. . this picture is hilarious.. it's the mold for my first flying sphere.. with a Coanda effect propulsion system.. .. but the instructions from China are.. droll.. says if the child collapse.. pull to shore immediately and resuscitate.. cracks me up every time.. look at the victim's face pin.it/6kZqR4r with a wing, my father told me the path traveled over the top is longer than the one under the wing, which creates a low pressure over the wing.. as long as it is moving forward at some minimum speed.. the stall point
I have always tried to understand the concept of this coanda effect and never managed to and then your video comes up and it's all crystal clear in just under 4 minutes. Awesomely done, great job.👍🏻
What an incredibly enlightening vedio I found ! I've never fully understood the Bernoulli effect and Coanda effect until now. The explanation provided was so clear and easy to follow. Huge thanks to the teacher for making these concepts so accessible!
It was a really great explanation! Coanda effect is often mentioned during f1 car aerodynamics analysis but I really didn't understand very well what the phenomena was like. Thanks to you now I know so thank you very much! :)
Its about dam time! This is awesome! how the hell did people expect others to like science if it wasn't explained as fast and striaght as this video! The guy just jumps right in with a visual and his explanation makes sence! Thank god!
The last case (the bottle) is not because the Coanda effect, but the surface tension of the liquid. Think that if you pour the wine extremely slowly it will stick too and there is no speed for Coanda effect.
I love how there are people like Wolfgang here, who go through the often difficult processes of learning or understanding something, and thinking "how can I make this easier for other people?". Thank you for the explanation!
The young romanian scientist/ genius observed this effect in 1910 when he was flying the first jet airplane in the world, that he designed at the age of 21. The engine was put in front of the pilot and in the flight he observed the jet of gas curving tovards the fuselage. It ignited it since it was made of ply-wood. He was lightly injured in the accident and he had some time to examine this effect of fluids.
I used to get free Public Library access to the Scientific American magazine back in the 60s. I have never forgotten the Coanda article. What a lucky and interested young fellow I was!
Explaining why there's a low pressure area and a high pressure area is the most important part of the video. It could have used more attention. So you're saying there's air being pulled into or with the main flow by friction, colliding with the air already in the flow. Normally this additional air enters the flow from all sides, so these collisions balance each other out and the flow remains straight. When a curved surface is introduced, air cannot enter from below because the surface is in the way, so air entering the flow from above knocks the whole flow down, following the curvature of the surface.
Navak regarding your last point about ‘air entering in from above’ it’s important to note that this doesn’t magically happen and that the cause of this is because the air below is moving down… As you said, the friction or ‘viscosity’ of the fluid will cause the air on the far side of the curved object to move away from the surface of the object. This creates a low pressure area below the air/fluid flow, and a normal pressure above the flow of the fluid. Now as there are more particles above that are hitting the particles within the flow of the fluid than below, it will have a net force downwards.
Wolfgang, thank you for making this so easy to understand. I've know about this effect for years and somewhat understood the science behind it.. Now I have a better grasp of what is going on. My motivation to revisit this stems from my building a small fume extractor to use when I am welding in my home workshop. I noticed that most of the professional fume extractors typically have a bell-mouth at the end of flexible duct on the suction side. Also, I have seen the same bell-mouth design on the suction side of fluid pumps and gas turbine engines. I am in the process of constructing a rectangular bell-mouth for my fume extractor. I went with this shape because it is the easiest to construct from 22 gauge sheet steel. A round bell-mouth would require special spinning machinery. I sized the small end to fit a standard 4" x 10" HVAC register boot that transitions from rectangular to 4" round. Hopefully, the Coanda effect will behave nicely with my custom bell-mouth.
Excellent! Within seconds I did understand what the Coanda Effect is, I did fast forward some seconds to the explanation of how it works and that was excellent. I read some text but didn't get it, but just after 20-ish seconds I got it from this video. Now I can perhaps read the articles and understand what they mean instead of getting headache
So proud for me to be a Romanian at this moment,just like Henri Coanda…the inventor of jet airplane,smoke tunnel,airplane wing part that facilitates drag and lift,and….the Coanda Effect.
Very nice visualization. I am confused though about the wine: is there really the Coanda effect that causes the wine to follow the bottle? isn't it mainly related to surface tension? just a quick search on wikipedia: 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 (for example, Massey in "Mechanics of Fluids"[47] uses the Coandă effect to explain the deflection of water around a cylinder). 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. Here, because it is a flow of water into air, there is little entrainment of the surrounding fluid (the air) into the jet (the stream of water). This particular demonstration is dominated by surface tension. (McLean in "Understanding Aerodynamics"[48] states that the water deflection "actually demonstrates molecular attraction and surface tension.")" Thank you!
You are right in thinking that it is more complicated than just the Coanda effect. Surface tension and adhesive forces certainly come into play. For example, if you make the glass hydrophobic (by smearing butter on the lip of the glass or cup), then the effect of the fluid's surface tension might predominate and the wine might not be drawn along the surface. That would be another way of thwarting the Coanda effect.
Moreover, most engineering books on aerodynamics don't even mention the Coanda effect. To be honest, I only heard about it after leaving college, when I had to study Theory of Flight and other subjects to get my private pilot's license.
Can you share your Schlieren setup? Curious about the lighting and lens settings. I am trying to film Schlieren but I only get shadows. I can’t seem to get the subject in focus nor lit up.
At around 2:55 when he has the hair dryer levitating the ball at an angle, what is causing this levitating effect? For this to work I assume that when the ball goes further down towards the ground (from its own weight) then the stream of air below/right the ball has to provide a greater force upwards/left to keep the ball stable and balanced. What is causing this increased force when the ball begins to fall outside the flow of air from the hair dryer?
As the hair dryer is tilted more and more, the ball starts to move out of the air stream as gravity pulls it down. But also notice that the air stream around the bottom of the ball wraps around it quite dramatically and is deflected up and back into the main air stream. This is caused by the Coanda Effect as described in the video - it is the surrounding air pressure (outside the air stream) that pushes the stream of moving air around the ball and back into the main stream. Because of viscosity, the moving air stream "drags" the ball with it. So in this case, air drag is responsible for forcing the ball back into the main air stream. Frictional forces can slow down motion and other times are responsible for motion (friction between the tire and the road can stop a car as well as get the car moving). Does that make sense?
Wolfgang Rueckner okay thanks I didn’t think about the friction. However my question still stands. Why is this system so stable? What causes the force pushing the ball towards the middle of the stream to increase as it starts to fall out? Is it that the speed of the air below the ball starts to increase somehow (when the ball begins to fall out), and so this increase in speed will increase the friction force supplied as there are more particles going past in a set time when compared to the top side of the ball?
@@alfredwilson1795 I think it's simply that the coanda effect increases as the ball tries to leave the air stream. Since it's the ambient atmospheric pressure that contributes to the coanda effect, then the answer to your question is that it's ultimately the higher atmospheric pressure outside the stream that is the origin of force. In the past, people have attributed the behavior to the Bernoulli effect and argued that since the pressure in the fast moving air stream is lower than the pressure of the slow moving surrounding air, the ball gets pushed back into the air stream because the higher pressure outside the stream pushes it back into the lower pressure inside the stream. That all makes sense except for the fact that none of the assumptions that are used to derive the Bernoulli effect are correct in this experiment. The Bernoulli effect assumes laminar flow (not turbulent) and a non-viscus fluid. Also, it only makes sense if you compare pressures moving along with the flow (not across the flow). All three of those assumptions are not true in this experiment.
Has this Coanda effect anything to do with wind travelling between two houses creating a differential air pressure thus the wind rushes around the back to equalise the difference? Thank you for video.
I just had someone dispute the coanda effect's relationship to airfoil lift, stating that coada applies only to jets of air ( like your hair dryer), not to larger air movement. But surely the entrainment principle still applies. True?
My understanding is that if all the air is moving past the solid surface uniformly-similar to a case where we had a hair dryer that was much, much wider than the diameter of the basketball-then the air would separate from the ball much sooner, because there wouldn't be enough entrainment of the surrounding air to make it conform to the curved surface. There are some aircraft, like the C-17 Globemaster III, that are able to use the Conanda effect to generate some extra lift by blowing air from its engines through holes in the airfoils.
Great vid but how is this different that Bernoulli's principle? The Boston MOS used to have a demonstration installed of what this guy does with the hair dryer and ping pong ball, and it was credited to Bernoulli
That demonstration (as well as many others) has often been wrongly explained by invoking the Bernoulli effect. The Bernoulli effect is a statement of conservation of mechanical energy. To apply it properly to a given situation, one assumes that the fluid is incompressible, is nonviscous, the flow of the fluid is laminar, and you are comparing the pressure changes following along the fluid flow lines (not across flow lines). In this case, air is compressible, air has viscosity, the air flow is turbulent, and people compare the pressure across flow lines! With these stringent prerequisites, one wonders if one can ever correctly apply the Bernoulli principle. It turns out it does remarkably well in some situations, even if all the prerequisites have not been strictly adhered to. In those cases where it seems to work anyway, it's a reasonably good approximation. In any case, the Coanda effect is a better model for explaining the experiments in this video.
What I also noticed with the ping pong ball demo was the ping pong ball axis didn't appear to change as the air flow tilted off C/L. I'm assuming gravity comes into play for that. It would be nice to see a F/U demo with a C/L scribed on the ping pong ball with a discussion relative to that. Keep up the good work.
And what about the boundary layer in the example with the basketball ball? Does is stick to the surface of the ball and then the rest of the airflow is pulled towards it, or is the whole airflow including boundary layer pulled towards the surface as a whole? Thank you.
Very interesting! This reminds me of reading rivers to find gold. I wonder why light, air, water and magnetic forces bend and sound deflects at angles?
John Frost tried to use this to concept to create thrust for aircraft in the form of a saucer! Why is the saucer not a functional usage of flying? Is it possible to develop a device that rides magnetic fields similarly as the pingpong ball rides on the air from the blow dryer?
With the hair dryer you were creating a low pressure area behind the ball. When liquid follows the surface of a container when poured, defying gravity, I would think that would mostly be the surface tension of the liquid . ? Are they both the coanda effect? Is the coanda effect the direct result of Bernoulli's principle? Is the coanda effect and bernoulli's principle the same thing. Ah, maybe I'm confusing an effect and a principle.?
Excellent Wolfgang! Are there limitations to the Coanda effect on something like a spiral shell? Say you take a sheet metal roll it into a spiral pattern with a few internal loops, would the air travel inside the spiral and come back out(like a smoke ring)?
The Coanda effect would come into play to help get the air to enter the spiral, but once inside the spiral I think the forces on the air flow would be similar to forces experienced in an air duct (reflections off walls, etc.). Fluid dynamics is really quite complicated.
You are right in thinking that it is more complicated than just the Coanda effect. Surface tension and adhesive forces certainly come into play in addition to the Coanda effect. For example, if you make the glass hydrophobic (by smearing butter on the lip of the glass or cup), then the effect of the fluid's surface tension might predominate and the wine might not be drawn along the surface. That would be another way of thwarting the Coanda effect.
@@wolfgangrueckner7151 Wiki (and McLean 2012 Aerodynamics) says that deflection of flow of water is not Coanda effect, but molecular attraction and surface tension: ... the cause is not really the Coandă effect. Here, because it is a flow of water into air, there is little entrainment of the surrounding fluid (the air) into the jet (the stream of water). This particular demonstration is dominated by surface tension. (McLean 2012, Figure 7.3.6 states that the water deflection "actually demonstrates molecular attraction and surface tension."). Thank you for the thought-provoking video :)
@@sdf420 You are quite right, Serge. Molecular attraction and surface tension are indeed the primary causes of the coffee running down the side of the cup (the Coanda effect being minor). The effect of molecular attraction can be alleviated to some extent by making the surface of the cup hydrophobic (buttering it). Providing a sharp edge that the coffee would have to turn around allows the liquid's inertia to overcome the attraction (like the wine bottle foil insert). But neither of those make for pleasant coffee drinking 🙂 Thank you for your illumination.
When does coanda effect is eliminated? How it co related to the velocity or acceleration of liquid? Consider pouring wine from bottle with perfect angle or speed without observing coanda effect
Yes, just a question, if we did the same experiment in a large vacuum chamber with a pressurized tank in place of the hairdryer, will the coanda effect immediately happen on the surface of the cylinder without any ambient air pressure?
All the effects allotted to Bernoulli, Newton and Coanda, owe their activity to Fluid mass being accelerated in a straight lines or around a curved surface. Fluid has a viscosity (elasticity) and small volumes can be subjected to compression or to tension, resulting in the associated pressures or forces. If the viscosity holds, the tension, then we have laminar flow, if it does not, turbulent states exist. If a mass of air has a velocity vector, it tends to try to keep going straight on, if at a later stage it flows near a surface that curves away, the air mass tends to keep going straight and if the sheet of air flow " seals" itself, then the fluid between the sheet of air and the curve, is tensioned and so this is what pulls the moving air to the curve. The upper surface of a wing. If it happens that moving air hits a surface as the lower surface of a wing then the fluid particles under the wing are in compression and so they accelerate the air downwards. Those above the wing are in tension and so they accelerate the mass of air downwards. Bernoulli, Newton, Coanda effets are due to ACCEPERATION FORCES applied to the mass flow of the fluid.
A beam of laser light when it meets the tangent of a smooth curved surface, when bending of the light occurs, does that qualify as the Coanda Effect? Light is neither fluid or gas. I'm not exactly sure of a tested result (of my question) but maybe somebody knows and can attach a link.
No, that does not qualify as the Coanda Effect. The laser beam will only bend if there is a gradient in the index of refraction of the medium (air, in this case).
So glad my battle with pouring coffee has a name
😂
I hate when this happens!
Yeah never paid attention to it
Tabarnak
Lol!
This is the best explanation for Coanda Effect. Perfect.
BERNOULLI'S EQUATION
@@drumtwo4seventhe Coanda effect explains something more than Bernoulli's equation alone
A perfectly clear demonstration of the Coanda Effect.
thank you
Excellent video about the Coanda effect!
thank you!
For those who don´t know , Henri Coandă was a Romanian inventor and aerodynamics pioneer.
Of course we know. Henri Coanda also invented Flying Soucer with methan. Every alien in Univers have one. :-))))
Great person.
They don't make them like that any more.
On winter break and was trying to build an RC airplane from scratch. I was so confused while learning aerodynamics on why air would follow a wing. This summed it up perfectly, than you Harvard!
it's the cause of low pressure over a wing.. but the wing requires forward motion... this effect create vertical lift on a bowl or saucer shape or a sphere, as we just saw.. it still takes work to move mass.. so... the air has to be really moving.. or the sphere really light.. like a soap bubble;;☆》.. . this picture is hilarious.. it's the mold for my first flying sphere.. with a Coanda effect propulsion system.. .. but the instructions from China are.. droll.. says if the child collapse.. pull to shore immediately and resuscitate.. cracks me up every time.. look at the victim's face
pin.it/6kZqR4r
with a wing, my father told me the path traveled over the top is longer than the one under the wing, which creates a low pressure over the wing.. as long as it is moving forward at some minimum speed.. the stall point
bro i've been looking for this explanation for 23 years
I have always tried to understand the concept of this coanda effect and never managed to and then your video comes up and it's all crystal clear in just under 4 minutes. Awesomely done, great job.👍🏻
thank you
Daniel Colombaro....This is exactly what i wanted to say....but i will continue my quest incase there is any other explanation for the effect
What an incredibly enlightening vedio I found ! I've never fully understood the Bernoulli effect and Coanda effect until now. The explanation provided was so clear and easy to follow. Huge thanks to the teacher for making these concepts so accessible!
I was checking for a coanda nozzle used in a milk spray dryer .Now I understand .Thanks for saving my time .
It was a really great explanation! Coanda effect is often mentioned during f1 car aerodynamics analysis but I really didn't understand very well what the phenomena was like. Thanks to you now I know so thank you very much! :)
You people are doing a great work by presenting the fascinating aspect of science ie practicals to students !!!
Salute from India 🇮🇳🇮🇳🇮🇳
Its about dam time! This is awesome! how the hell did people expect others to like science if it wasn't explained as fast and striaght as this video! The guy just jumps right in with a visual and his explanation makes sence! Thank god!
Congratulations on the clarity of explanation. So brief and yet so accurate. Well done, Sir.
thank you
Currently studying for a pilot exam. This demonstration helped a lot; so, thank you! 🙂
The last case (the bottle) is not because the Coanda effect, but the surface tension of the liquid. Think that if you pour the wine extremely slowly it will stick too and there is no speed for Coanda effect.
This is one of the best explanation of the Coanda effect. Thanks.
I love how there are people like Wolfgang here, who go through the often difficult processes of learning or understanding something, and thinking "how can I make this easier for other people?". Thank you for the explanation!
Generous good people
im glad this video exists its the perfect video for coanda effect i have been confused on it for years
The young romanian scientist/ genius observed this effect in 1910 when he was flying the first jet airplane in the world, that he designed at the age of 21. The engine was put in front of the pilot and in the flight he observed the jet of gas curving tovards the fuselage. It ignited it since it was made of ply-wood. He was lightly injured in the accident and he had some time to examine this effect of fluids.
Fake and bullshit. Coanda was a notorious liar. He never fly a jet plane.
You forgot to mention his name, Henri Coandă.
@@nickbarton3191it was implied by the video and name of the effect.
Proud to be a 🇷🇴 Romanian as Henri Coandã. The romanian inventor who discover the first jet engine.
Looks like you foiled the Coanda's plans to drip in the end! Well done! xD
I used to get free Public Library access to the Scientific American magazine back in the 60s. I have never forgotten the Coanda article.
What a lucky and interested young fellow I was!
日本の高校の理科教師です。発泡スチロール球を使って同じような実験を生徒たちと楽しみました。ピンポン球の実験は、5cmの発泡スチロール球を使うともっと上がって感動的です。
Thanks. Was reading about the Kings Cross fire in London in 1987 and noted this effect was significant in how the fire progressed so rapidly.
This is the greatest video on the conada effect that I've ever seen. Thank you, sir.
*coanad
For the first time I understand the Coanda effect! Thank you!
Glad to hear it!
That was a cool demonstration of Conanda effect!
Thank you. Exactly what i was looking for
Explaining why there's a low pressure area and a high pressure area is the most important part of the video. It could have used more attention.
So you're saying there's air being pulled into or with the main flow by friction, colliding with the air already in the flow. Normally this additional air enters the flow from all sides, so these collisions balance each other out and the flow remains straight. When a curved surface is introduced, air cannot enter from below because the surface is in the way, so air entering the flow from above knocks the whole flow down, following the curvature of the surface.
that's a good way of thinking about it
Wait, so why do fluids stick to the shape of convex objects?
You really put it in a way that made me instantly understand it. Thank you.
Navak regarding your last point about ‘air entering in from above’ it’s important to note that this doesn’t magically happen and that the cause of this is because the air below is moving down…
As you said, the friction or ‘viscosity’ of the fluid will cause the air on the far side of the curved object to move away from the surface of the object. This creates a low pressure area below the air/fluid flow, and a normal pressure above the flow of the fluid.
Now as there are more particles above that are hitting the particles within the flow of the fluid than below, it will have a net force downwards.
Wolfgang, thank you for making this so easy to understand. I've know about this effect for years and somewhat understood the science behind it.. Now I have a better grasp of what is going on. My motivation to revisit this stems from my building a small fume extractor to use when I am welding in my home workshop. I noticed that most of the professional fume extractors typically have a bell-mouth at the end of flexible duct on the suction side. Also, I have seen the same bell-mouth design on the suction side of fluid pumps and gas turbine engines. I am in the process of constructing a rectangular bell-mouth for my fume extractor. I went with this shape because it is the easiest to construct from 22 gauge sheet steel. A round bell-mouth would require special spinning machinery. I sized the small end to fit a standard 4" x 10" HVAC register boot that transitions from rectangular to 4" round.
Hopefully, the Coanda effect will behave nicely with my custom bell-mouth.
This explanation here really flowed well
Awesome Explanation
Excellent! Within seconds I did understand what the Coanda Effect is, I did fast forward some seconds to the explanation of how it works and that was excellent. I read some text but didn't get it, but just after 20-ish seconds I got it from this video. Now I can perhaps read the articles and understand what they mean instead of getting headache
Beautiful demonstration and explanation
Thanks for this lucid description.
So proud for me to be a Romanian at this moment,just like Henri Coanda…the inventor of jet airplane,smoke tunnel,airplane wing part that facilitates drag and lift,and….the Coanda Effect.
Usor cu laudele,inventatorii jetului au fost mai multi,printre care si Coanda.Doar romanii il considera primul.
HAHAHA!! Thank you so much! Very good explanation! I avoid the Coanda effect in my wine bottle, drinking directly from the bottle!
Very nice visualization. I am confused though about the wine: is there really the Coanda effect that causes the wine to follow the bottle? isn't it mainly related to surface tension?
just a quick search on wikipedia:
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 (for example, Massey in "Mechanics of Fluids"[47] uses the Coandă effect to explain the deflection of water around a cylinder). 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. Here, because it is a flow of water into air, there is little entrainment of the surrounding fluid (the air) into the jet (the stream of water). This particular demonstration is dominated by surface tension. (McLean in "Understanding Aerodynamics"[48] states that the water deflection "actually demonstrates molecular attraction and surface tension.")"
Thank you!
You are right in thinking that it is more complicated than just the Coanda effect. Surface tension and adhesive forces certainly come into play. For example, if you make the glass hydrophobic (by smearing butter on the lip of the glass or cup), then the effect of the fluid's surface tension might predominate and the wine might not be drawn along the surface. That would be another way of thwarting the Coanda effect.
andipelamine true..
Moreover, most engineering books on aerodynamics don't even mention the Coanda effect. To be honest, I only heard about it after leaving college, when I had to study Theory of Flight and other subjects to get my private pilot's license.
Well, he said it himself that he understood what was going on when he saw a drop of water sliding on his finger
Can you share your Schlieren setup? Curious about the lighting and lens settings. I am trying to film Schlieren but I only get shadows. I can’t seem to get the subject in focus nor lit up.
what a great demonstration😍
Thank you so much❣
I love your videos you explain so well!
The Coanda effect is used in the aerodymanics (engine-wing area) of Antonov An-72/-74 aircraft.
Or more generally to generate lift in every aircraft.
Coanda effect also important in high rise building fires as hot fire gases cling to the building exterior when venting from windows
Crystal explanation. Thanks.
Perfect introduction !
Thanks for the wonderful video. You couldn't have made it any clearer, sir.
At around 2:55 when he has the hair dryer levitating the ball at an angle, what is causing this levitating effect?
For this to work I assume that when the ball goes further down towards the ground (from its own weight) then the stream of air below/right the ball has to provide a greater force upwards/left to keep the ball stable and balanced.
What is causing this increased force when the ball begins to fall outside the flow of air from the hair dryer?
As the hair dryer is tilted more and more, the ball starts to move out of the air stream as gravity pulls it down. But also notice that the air stream around the bottom of the ball wraps around it quite dramatically and is deflected up and back into the main air stream. This is caused by the Coanda Effect as described in the video - it is the surrounding air pressure (outside the air stream) that pushes the stream of moving air around the ball and back into the main stream. Because of viscosity, the moving air stream "drags" the ball with it. So in this case, air drag is responsible for forcing the ball back into the main air stream. Frictional forces can slow down motion and other times are responsible for motion (friction between the tire and the road can stop a car as well as get the car moving). Does that make sense?
Wolfgang Rueckner okay thanks I didn’t think about the friction. However my question still stands. Why is this system so stable? What causes the force pushing the ball towards the middle of the stream to increase as it starts to fall out? Is it that the speed of the air below the ball starts to increase somehow (when the ball begins to fall out), and so this increase in speed will increase the friction force supplied as there are more particles going past in a set time when compared to the top side of the ball?
@@alfredwilson1795 I think it's simply that the coanda effect increases as the ball tries to leave the air stream. Since it's the ambient atmospheric pressure that contributes to the coanda effect, then the answer to your question is that it's ultimately the higher atmospheric pressure outside the stream that is the origin of force.
In the past, people have attributed the behavior to the Bernoulli effect and argued that since the pressure in the fast moving air stream is lower than the pressure of the slow moving surrounding air, the ball gets pushed back into the air stream because the higher pressure outside the stream pushes it back into the lower pressure inside the stream. That all makes sense except for the fact that none of the assumptions that are used to derive the Bernoulli effect are correct in this experiment. The Bernoulli effect assumes laminar flow (not turbulent) and a non-viscus fluid. Also, it only makes sense if you compare pressures moving along with the flow (not across the flow). All three of those assumptions are not true in this experiment.
very specified, very nice description
Has this Coanda effect anything to do with wind travelling between two houses creating a differential air pressure thus the wind rushes around the back to equalise the difference? Thank you for video.
Brilliant demonstration.
Thank you for the wonderful explanation!
Could the adhesion between the ball and the air also be one of the reasons for the Coanda effect?
I just had someone dispute the coanda effect's relationship to airfoil lift, stating that coada applies only to jets of air ( like your hair dryer), not to larger air movement. But surely the entrainment principle still applies. True?
My understanding is that if all the air is moving past the solid surface uniformly-similar to a case where we had a hair dryer that was much, much wider than the diameter of the basketball-then the air would separate from the ball much sooner, because there wouldn't be enough entrainment of the surrounding air to make it conform to the curved surface. There are some aircraft, like the C-17 Globemaster III, that are able to use the Conanda effect to generate some extra lift by blowing air from its engines through holes in the airfoils.
@@NatSciDemos Thanks.,.I will ponder that.
I mispelled Conan Grey's name to "Coan" and it recommends "Coanda effect" and now Im here learning new thing
Great explanation with engeeniring solution :)
Glad you liked it!
Thank you! Instant sub. Looking forward to more.
Thanks! Now I can pour.
Sir salute, finally i found this video
I’m here because of the new hair dryer from Dyson ahaha
Me too 😂😂
Same
Same
Yup LOL
Me too, hahaha 😂
Great video. 👍
Great vid but how is this different that Bernoulli's principle? The Boston MOS used to have a demonstration installed of what this guy does with the hair dryer and ping pong ball, and it was credited to Bernoulli
That demonstration (as well as many others) has often been wrongly explained by invoking the Bernoulli effect. The Bernoulli effect is a statement of conservation of mechanical energy. To apply it properly to a given situation, one assumes that the fluid is incompressible, is nonviscous, the flow of the fluid is laminar, and you are comparing the pressure changes following along the fluid flow lines (not across flow lines). In this case, air is compressible, air has viscosity, the air flow is turbulent, and people compare the pressure across flow lines! With these stringent prerequisites, one wonders if one can ever correctly apply the Bernoulli principle. It turns out it does remarkably well in some situations, even if all the prerequisites have not been strictly adhered to. In those cases where it seems to work anyway, it's a reasonably good approximation. In any case, the Coanda effect is a better model for explaining the experiments in this video.
it's the Koalanda effect in Australia
What I also noticed with the ping pong ball demo was the ping pong ball axis didn't appear to change as the air flow tilted off C/L. I'm assuming gravity comes into play for that. It would be nice to see a F/U demo with a C/L scribed on the ping pong ball with a discussion relative to that. Keep up the good work.
Thank you!
Best explanation I loved!!!!
Thank you, great video!
I would be very interested in knowing how to do the Slewing Mirror for making a wind tunnel myself, could you give me a lil guide?
And what about the boundary layer in the example with the basketball ball? Does is stick to the surface of the ball and then the rest of the airflow is pulled towards it, or is the whole airflow including boundary layer pulled towards the surface as a whole? Thank you.
Very interesting! This reminds me of reading rivers to find gold. I wonder why light, air, water and magnetic forces bend and sound deflects at angles?
John Frost tried to use this to concept to create thrust for aircraft in the form of a saucer! Why is the saucer not a functional usage of flying? Is it possible to develop a device that rides magnetic fields similarly as the pingpong ball rides on the air from the blow dryer?
How were you showing the flow of air
The technique is called schlieren optics. You can read the details here: sciencedemonstrations.fas.harvard.edu/presentations/schlieren-optics
Wolfgang Rueckner Thanks for the valuable information 🙂
Sir
How can i get (Schlieren Optics)
And how its cost ?
With the hair dryer you were creating a low pressure area behind the ball.
When liquid follows the surface of a container when poured, defying gravity, I would think that would mostly be the surface tension of the liquid . ?
Are they both the coanda effect? Is the coanda effect the direct result of Bernoulli's principle?
Is the coanda effect and bernoulli's principle the same thing.
Ah, maybe I'm confusing an effect and a principle.?
What about the floating screwdriver videos? People using an air nozzle and getting a screwdriver to float ? Is this the same effect ?
Good explanation !
Mas claro que esto; imposible!
Gran aporte señor 👏🗿
How does flow curve around a surface if viscosity is zero, such as potential flow around a transverse cylinder.?
Excellent Wolfgang! Are there limitations to the Coanda effect on something like a spiral shell? Say you take a sheet metal roll it into a spiral pattern with a few internal loops, would the air travel inside the spiral and come back out(like a smoke ring)?
The Coanda effect would come into play to help get the air to enter the spiral, but once inside the spiral I think the forces on the air flow would be similar to forces experienced in an air duct (reflections off walls, etc.). Fluid dynamics is really quite complicated.
Very well explained, thank you :)
What is that thing in the background?
great explanation and great trick not to spil the wine...
when wine drips down the bottle, is it a Coanda effect? or surface tension ?
You are right in thinking that it is more complicated than just the Coanda effect. Surface tension and adhesive forces certainly come into play in addition to the Coanda effect. For example, if you make the glass hydrophobic (by smearing butter on the lip of the glass or cup), then the effect of the fluid's surface tension might predominate and the wine might not be drawn along the surface. That would be another way of thwarting the Coanda effect.
It's related to the flow rate.
@@wolfgangrueckner7151 Wiki (and McLean 2012 Aerodynamics) says that deflection of flow of water is not Coanda effect, but molecular attraction and surface tension:
... the cause is not really the Coandă effect. Here, because it is a flow of water into air, there is little entrainment of the surrounding fluid (the air) into the jet (the stream of water). This particular demonstration is dominated by surface tension. (McLean 2012, Figure 7.3.6 states that the water deflection "actually demonstrates molecular attraction and surface tension.").
Thank you for the thought-provoking video :)
@@sdf420 You are quite right, Serge. Molecular attraction and surface tension are indeed the primary causes of the coffee running down the side of the cup (the Coanda effect being minor). The effect of molecular attraction can be alleviated to some extent by making the surface of the cup hydrophobic (buttering it). Providing a sharp edge that the coffee would have to turn around allows the liquid's inertia to overcome the attraction (like the wine bottle foil insert). But neither of those make for pleasant coffee drinking 🙂 Thank you for your illumination.
When does coanda effect is eliminated? How it co related to the velocity or acceleration of liquid?
Consider pouring wine from bottle with perfect angle or speed without observing coanda effect
Great work! Very easy to understand!
Nice explaination!
Does the candle exhibit Coanda?
i love the dark aesthetic.
Yes, just a question, if we did the same experiment in a large vacuum chamber with a pressurized tank in place of the hairdryer, will the coanda effect immediately happen on the surface of the cylinder without any ambient air pressure?
No, it will not.
Would liquid from a bottle being poured not be a capillary response instead of air flow response?
Hey Wolfy, bet that's the only time your hairdryer see's the light of day.
Can anyone please tell me what that screen which is capturing the air flow is and how I can build it?
It's a schlieren optics system. There's a link in the description for more details.
excellent video! Thank you.
All the effects allotted to Bernoulli, Newton and Coanda, owe their activity to Fluid mass being accelerated in a straight lines or around a curved surface. Fluid has a viscosity (elasticity) and small volumes can be subjected to compression or to tension, resulting in the associated pressures or forces. If the viscosity holds, the tension, then we have laminar flow, if it does not, turbulent states exist.
If a mass of air has a velocity vector, it tends to try to keep going straight on, if at a later stage it flows near a surface that curves away, the air mass tends to keep going straight and if the sheet of air flow " seals" itself, then the fluid between the sheet of air and the curve, is tensioned and so this is what pulls the moving air to the curve. The upper surface of a wing.
If it happens that moving air hits a surface as the lower surface of a wing then the fluid particles under the wing are in compression and so they accelerate the air downwards. Those above the wing are in tension and so they accelerate the mass of air downwards.
Bernoulli, Newton, Coanda effets are due to ACCEPERATION FORCES applied to the mass flow of the fluid.
Molecules that are dragged away can not be replaced as fast as the ones without an object to block incoming ones. I assume.
Simple and clear. Nice !
protect this man at all costs
Still don't know how to avoid the coanda effect while pouring coffee from one thick wall mug to another. Any ideas?
Fantastic! How the relation with solar wind and gravity?
A beam of laser light when it meets the tangent of a smooth curved surface, when bending of the light occurs, does that qualify as the Coanda Effect? Light is neither fluid or gas.
I'm not exactly sure of a tested result (of my question) but maybe somebody knows and can attach a link.
No, that does not qualify as the Coanda Effect. The laser beam will only bend if there is a gradient in the index of refraction of the medium (air, in this case).
He may be referring to a diffraction effect, which can also give the appearance that light is bending (or deflecting) around an obstacle.
Awesome sir!
thank you
Henri Coanda--way ahead of his time. Imagine if he had rolled out his aircraft in the late 30s when gearing up for WW2? Thanks!
Thanks for crystal explanation.
Well done. Thank you.
Thank you for an Effective Explanation on Coanda.