A small correction. A fluid tends to move from a high pressure region to a low pressure region, for instance the wing tip vortex. So, the adverse pressure gradient is when the fluid moves to a relatively higher pressure (dp/dx > 0), contrary to what was stated at 3:05.
Because of friction the speed of the particle sticking to the surface is zero, as we move further the friction is no longer applicable so the speed increases.
Hello, what I do not understand is why you said laminar boundary layer is to reduce the drag at first, but then gave an example of golf and tennis ball that holes on them were made to create turbulent flow to reduce drag. I feel lost on the concept that its is turbulent or laminar flow which can reduce the drag. Hope you can answer me , thank you !
do you mean the pressure drag creating by turbulent flow for golf and tennis, but skin friction drag creating by laminar flow, there are two different drags which may make sense.
If we consider a smooth body, a laminar flow is required since it will stick to the surface, however if we consider a bluff body a turbulent flow is required, which will cause the flow to stick to the surface! This will reduce the drag!! Hope it helps!
@@JxJAVIATION Oh, so you mean it really depends on surface roughness, is it related to the Moody chart in Fluid Mechanics? Thanks for answering, awesome videos ! Will keep watching and learning as an entry level aircraft engineer ! !
@@Airlynch077 In case of balls, the flow separation is worse than the added drag for a turbulent boundary layer. Since we can't make them not balls, that's our best bet. For everything else just avoid flow separation
📝 Summary of Key Points: 📌 The boundary layer is a thin layer of fluid that forms on the surface of an object as it moves through a fluid, caused by friction between the fluid and the surface. 🧐 There are two types of boundary layers: laminar and turbulent. Laminar boundary layers reduce skin friction drag and improve aerodynamic efficiency, while turbulent boundary layers are thicker and cause more skin friction drag but can withstand adverse pressure gradients and prevent flow separation. 🚀 Understanding the boundary layer is crucial for optimizing the aerodynamic efficiency of objects like aircraft wings and sports equipment. 💡 Additional Insights and Observations: 💬 "The boundary layer only forms in a viscous fluid." 📊 Laminar boundary layers reduce skin friction drag, while turbulent boundary layers cause more skin friction drag but can withstand adverse pressure gradients. 🌐 References and Sources: The video does not mention any specific references or sources. 📣 Concluding Remarks: The boundary layer is a significant concept in fluid dynamics that affects the movement of objects through fluids. Understanding the different types of boundary layers and their impact on drag and flow separation is crucial for optimizing the aerodynamic efficiency of various objects. Made by Talkbud
It isn't clear in a short video how the golf ball dimples which reduce pressure drag outweigh friction drag. And also why there would be a high and low pressure on the upper wing surface if there is laminar flow. Or what causes the high pressure on the upper wing surface. Or what is it about a laminar boundary layer which makes separated flow more likely?
This is fine for a wind tunnel, but for real flying, the air is stationary and the wing moves at high velocity so the particle touching the wing is moving fast One can say that the viscous air particles around the wing ar subjected to tension or compression due to diverse effects. If the tension holds the flow is laminar, If it does not hold then the flow becomes turbulent. Let us assume the conventional shape of an airfoil section has a slight angle of attack. As the foil moves forward, the lower surface is pushing the air down but also forward =and the air below the wind has a downward component in addition to a horizontal component (In a wind tunnel the lower surface slows down the horizontal airflow because of the angle of attack while reflecting the flow downwards). As the air moves above the wing, it enters a divergent shape, the divergent shape causes a downward velocity to be created in addition to the horizontal velocity. There is a pressure zone above the leading edge to accentuate the down acceleration at a later stage. Because of the tapered nature of the upper surface of the wing, towards the trailing edge, the longer vertical distance permits the air particles to gain a higher downward vertical velocity and so this results in the flow above the wing is faster than the flow under the wing. Note1 that when dealing with lift and drag and control surceases and propeller thrust, one should always deal with the acceleration of the mass particles at any point around the unit in question. It is acceleration that creates force, not velocity or location. Note 2.. An adverse pressure gradient is a pressure gradient in which the static pressure increases in the direction of the flow.
The authors have two wrong scientific approaches: researching the creation of Lift force and Low pressure at upper side of the wing, relative to the ground surface and Earth. I explain the aerodynamic cavitation and existence of Lee side aerocavern, and creation of Aerodynamic force. Low pressure creates force normal to the cord (contact surface), and it name is "aerodynamic force" because is made from the air (aero) in motion (dynamic), or wind relative to the wing (object).
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A small correction. A fluid tends to move from a high pressure region to a low pressure region, for instance the wing tip vortex. So, the adverse pressure gradient is when the fluid moves to a relatively higher pressure (dp/dx > 0), contrary to what was stated at 3:05.
Yes. Good observation! Thank you!
That video was great ! I was struggling with the boundary layer a lot and I understand way better now
Thanks !!
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One of the best videos for education , very simple and good explanation
Sir please make more videos like this
Thank you!! Please do check out my other videos as well!
I needed some clarification on this topic. Very informative, thank you!
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your video helped me lot thanks for sharing knowledge i am doing PHD
What is your Ph.D topic
Awesome and All the Best!! Thank you! Check out my other video as well!
BOUNDARY LAYER FLOW SEPARATION
Thank you Sir for your valuable and excellent explanation. It really got my concepts cleared !!!
Please#KEEP UP THE GOOD WORK !!! 😃👍🍫
You're most welcome! Check out my other videos as well!
Very well explained and great graphics; thanks for posting.
You're very welcome!
Great and nice explanatory information. Very great.
Thank you! Check out my other video as well!
Thank you a lot for this bank of information, I really appreciated.
Thank You! Check out my other videos as well!
Really, today I got know about the vortex generators,Thank you sir.
You are welcome! Check out my other videos as well!
thankyou. best video on this topic! clearly understood everything!
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thank you for such a simple explonetion. i hope you will continuo recording videos
Thank You! Check out my other videos as well!
This very helped me alot thanks
Glad it helped
At 1:32 , why does the speed of the air particles gradually increase?
Because of friction the speed of the particle sticking to the surface is zero, as we move further the friction is no longer applicable so the speed increases.
Always the best explanation
Thanks! 😃
Thank u very mucch for the best explanation
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Thank you so much!
Thank you! Check out my other videos as well!
Super good explained
Thank you. Check out my other videos as well!
Hello, what I do not understand is why you said laminar boundary layer is to reduce the drag at first, but then gave an example of golf and tennis ball that holes on them were made to create turbulent flow to reduce drag. I feel lost on the concept that its is turbulent or laminar flow which can reduce the drag. Hope you can answer me , thank you !
do you mean the pressure drag creating by turbulent flow for golf and tennis, but skin friction drag creating by laminar flow, there are two different drags which may make sense.
If we consider a smooth body, a laminar flow is required since it will stick to the surface, however if we consider a bluff body a turbulent flow is required, which will cause the flow to stick to the surface! This will reduce the drag!! Hope it helps!
@@JxJAVIATION Oh, so you mean it really depends on surface roughness, is it related to the Moody chart in Fluid Mechanics? Thanks for answering, awesome videos ! Will keep watching and learning as an entry level aircraft engineer ! !
@@Airlynch077 In case of balls, the flow separation is worse than the added drag for a turbulent boundary layer. Since we can't make them not balls, that's our best bet. For everything else just avoid flow separation
Where is start from boundary layer seperation leading edge or trailing edge
Great video🙌🏼
Thank you 🙌 Check out my other videos as well!
📝 Summary of Key Points:
📌 The boundary layer is a thin layer of fluid that forms on the surface of an object as it moves through a fluid, caused by friction between the fluid and the surface.
🧐 There are two types of boundary layers: laminar and turbulent. Laminar boundary layers reduce skin friction drag and improve aerodynamic efficiency, while turbulent boundary layers are thicker and cause more skin friction drag but can withstand adverse pressure gradients and prevent flow separation.
🚀 Understanding the boundary layer is crucial for optimizing the aerodynamic efficiency of objects like aircraft wings and sports equipment.
💡 Additional Insights and Observations:
💬 "The boundary layer only forms in a viscous fluid."
📊 Laminar boundary layers reduce skin friction drag, while turbulent boundary layers cause more skin friction drag but can withstand adverse pressure gradients.
🌐 References and Sources: The video does not mention any specific references or sources.
📣 Concluding Remarks:
The boundary layer is a significant concept in fluid dynamics that affects the movement of objects through fluids. Understanding the different types of boundary layers and their impact on drag and flow separation is crucial for optimizing the aerodynamic efficiency of various objects.
Made by Talkbud
That is awesome. Thank you! Check out my other videos as well!
@@JxJAVIATION Ok, I'll ;)
Nice video 👍
Thank you!! Check out my other videos as well!
It isn't clear in a short video how the golf ball dimples which reduce pressure drag outweigh friction drag. And also why there would be a high and low pressure on the upper wing surface if there is laminar flow. Or what causes the high pressure on the upper wing surface. Or what is it about a laminar boundary layer which makes separated flow more likely?
You can make this material as a sticker if you want to play with it...
there are different theories that discuss both the wings and the golf ball aerodynamics
thanks for this
You're welcome
This is fine for a wind tunnel, but for real flying, the air is stationary and the wing moves at high velocity so the particle touching the wing is moving fast
One can say that the viscous air particles around the wing ar subjected to tension or compression due to diverse effects. If the tension holds the flow is laminar, If it does not hold then the flow becomes turbulent.
Let us assume the conventional shape of an airfoil section has a slight angle of attack. As the foil moves forward, the lower surface is pushing the air down but also forward =and the air below the wind has a downward component in addition to a horizontal component (In a wind tunnel the lower surface slows down the horizontal airflow because of the angle of attack while reflecting the flow downwards).
As the air moves above the wing, it enters a divergent shape, the divergent shape causes a downward velocity to be created in addition to the horizontal velocity. There is a pressure zone above the leading edge to accentuate the down acceleration at a later stage. Because of the tapered nature of the upper surface of the wing, towards the trailing edge, the longer vertical distance permits the air particles to gain a higher downward vertical velocity and so this results in the flow above the wing is faster than the flow under the wing.
Note1 that when dealing with lift and drag and control surceases and propeller thrust, one should always deal with the acceleration of the mass particles at any point around the unit in question. It is acceleration that creates force, not velocity or location.
Note 2.. An adverse pressure gradient is a pressure gradient in which the static pressure increases in the direction of the flow.
thank you for the detailed explanation
I always thought that a turbulent boundary layer causes early air separation, a bad thing.
Turbulent boundary layer over a smooth surface is a bad thing
Skill issue. ( this is revenge for Simon from the 8 weens
haha
The authors have two wrong scientific approaches: researching the creation of Lift force and Low pressure at upper side of the wing, relative to the ground surface and Earth. I explain the aerodynamic cavitation and existence of Lee side aerocavern, and creation of Aerodynamic force. Low pressure creates force normal to the cord (contact surface), and it name is "aerodynamic force" because is made from the air (aero) in motion (dynamic), or wind relative to the wing (object).
Thanks for the info!
@@JxJAVIATION Thank you too, I send you an email, please check.