Physics 34 Fluid Dynamics (19 of 24) The Drag Coefficient
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- Опубликовано: 24 мар 2015
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In this video I will explain how different shaped objects have different drag coefficients.
Next video in this series can be seen at:
• Physics 34 Fluid Dyna...
Force of gravity: dont worry we will go through the fluid just fine nothing can stop me
Buoyant force, viscosity and drag force: *PILLARMEN THEME*
"Streamlined Body" also looks a lot like the body of a fish! Nice video. Thanks for sharing.
Excellent and thought provoking! Thanks.
Wonderful lecture. Thank you very much for making and contributing these.
Really nice teaching skills!
That was the best video ever!Thank you!😀😎
thank you very much you are a great teacher with the clear and simple explanation
Gute besserung Herr van Biezen. Thanks for nice teaching
thank you so much!! it's really useful.
Can drag pull fluid out of a tube by its force via an airstream brushing the tube's mouth, going "outward"?
thank you Sir，I have a few questions:
is the fluid still or kinetic,If the fluid is kinetic what should we do？the case will be more complicated I think，the fluid is moving, there are three conditions for sphere,1.floating on the surface of the fluid, 2.Submerged in the fluid but not at the bottom，3. on the bottom,so for these three cases,how to proceed to motion and force analysis?
does hydrodynamic drag coefficient is different from aerodynamic drag coefficient for same object. just say I took a hemisphere in air and underwater does Cd value change or any other considerations i have to take to find out the same
Is there a drag co-efficient for a rectangular shape?
Hi DOCTOR
Could you please tell me what is the project area for cylinder, sphere and each single ship i will really thankful?
I have a question regarding the formula used to calculate the drag force in this video. From a previous video about the Stoke's law, the equation used to calculate drag force of a sphere is FD=6πμRv, whereas is shown as a different equation in this one. Why are there different exponents of v in the two equations? Are they referring to the same concept? Thanks.
And Cd depends on Reynolds numbers right?
excellent lecture, thank you
Hey could you help me please I want to calculate Cx and Cz (drag and lift coefficient) of a 46m/s wind speed at an inclined panel with 30° incidence angle the force should be daN/m² or we could calculate the Drag and lift force on a panel of a 1.7x1 = 1.7m² area. SEARCHING SINCE A WEEK BUT NOTHING FOUND ON INTERNET. MECAFLUX software GIVES An automatic RESULT BUT I couldn't calculate manually.
These Drag coefficients are also strongly Reynolds number related, aren't they? In the case shown it could be 10^4. Might be worth mentioning
Wow thanks you are awesome! Can you also teach me how to find the coefficients of lift?😄
what exactly is the border line between long cylinder and short cylinder....?
If I recall it's relative to the cross sectional area vs length!
I am having trouble to determine drag force with my question regarding raising ball viscometer.....what is happened now if i change the movement of ball which i pull it out from the liquid (the movement of ball in the fluid will become upward) ,does drag force still exist here on the ball and where is the direction of it?
Drag force exist whenever the object is moving and the direction of the drag force will be opposite to the direction of motion.
'Very' well explained!!! Thankyou!! : )
Thank you. Glad you liked the video! 🙂
Open my understanding after 27 years read fluid mechanics book by Franzini
I had a quick question. How do we calculate the drag coefficient if we had multiple objects combined, like a cone on top of a long cylinder?
Drag coefficients are typically experimentally determined.
Doesn't the coefficient depend on the orientation of the object? It's not clear in which direction the drawn shapes are moving... Is it downward of left to right or right to left? Won't objects like the half sphere or the cone or any object automatically take on the lowest coefficient? Sorry I started writing this before the end of the video; hopefully it's all explained later!
Yes, you are correct, it does depend on the orientation. when these experiments are done to determine the coefficients, the orientation is controlled.
How come drag force is half of jet force rho A v^2?
The frontal area is the most important factor all other things can be tuned
Cd is also dimensionless quantity right?
Yes
i am confused why is there different formulas about the force of drag one is the stokes law and this why two different ons ????? i am confused please help!!!!!
This formula is used to calculate the drag forces on an object moving through a fluid.
ok i understood the difference after watching your videos on comparing them thanks anyways!
i am here on my quest to find out the time taken by an object to reach the ground when dropped from a height h taking drag into consideration. i can find the terminal velocity using Vt= square root(2mg/C rho A). But i am confused as to how to find the time taken by the object to reach its terminal velocity. Can anyone please help me or at least suggest a place where i can find my answer?
We have those types of videos in the differential equations videos, because that requires differential equations to work those out.
@@MichelvanBiezen Thank you sir, i'll check out those videos.
sir what is the difference between the viscous force and the drag force ?
They are off course related, but there is a distinction. The viscous force is caused by the "friction forces" between the fluid molecules. (the more the molecules are attracted to one another the greater the viscosity). The drag forces are caused by an object moving through a fluid and it depends on the velocity and the shape of the object.
Michel van Biezen thank you very much sir .
why does it jump from 17\25 to 19\32?
It looks like we skipped one by accident.
I'm 14, so I'm going to get easily confused, but how do you work out the drag coefficient that relates to the shape? For example, how can you work that a cube has 1.05 drag coefficient?
By the way, I'm trying to find out about acceleration and lengths objects get over time, with other forces pushing against the acceleration. I would like to easily be able to answer a question like this: a man is 350m high. He drops a cube made of pure copper. The cube is 64cm squared. (I'm guessing you can work out the mass and density of the cube) the density of the air is 1.2kg/m cubed. How long will it take for the object to hit the ground, keeping in mind that the gravitational acceleration is 9.8m/s squared. I think this is enough data.
Drag coefficients are experimentally determined.
Michel van Biezen OK thanks! I won't be doing that then haha. Great video by the way.
S=ut + 0.5at^2
Since u=0 at start, the equation can simply be written as, s=0.5gt^2. Where "s" represents displacement.
Use this formula to get your answer. Most of your given data is useless in thks calculation i guess.
Great!
🙂
suddenly got here after watching some One Piece videos lol. I absolutely know nothing abt this but it's interesting. So here's a noob question on a "logical" sense of mine.. Why do the cone shape got higher drag coefficient than the half-sphere ? I mean.. it's pointier than the half-sphere and the half sphere surface is wider. Does the rear shape affects how great can it slice through fluid ? sorry if this ticks off anybody lol just curious
That is a really good question. Understanding the drag on objects is very complicated. It is usually easier to place an object in a wind tunnel and look at the results, rather than trying to calculate it. It turns out that the drag on an object has a lot to do with the shape of the back. Note how cars that are very fuel efficient do have an abrupt square back, to reduce drag.
ah ! now i remember, the Toyota Prius ! that one have quite a good reputation on being a fuel efficient car. Thanks for the explanation ! :) great vid sir 👍👍
Kawasaki Nerd - If I may add an engineering perspective... First, I consider Mr. van Biezen to be one of the very best instructors, ever. Now, sometimes engineering must make practical compromises that do not adhere to theoretical optimums. The back end of cars must be crash - worthy (with bumpers) and accommodate cargo (in trunks). But notice that solar-powered cars in research competitions are often shaped like a manta ray, tapered to a thin edge in back. The goal is to reduce energy-stealing induced drag caused by vortices at the rear of a vehicle. There are a few tractor-trailer rigs on the road now that have a huge, rounded fiberglass fairing above the bumper that covers the rear doors of the trailer. Apparently the fairing expense was justifiable, given the huge, flat trailing surface (perpendicular to vehicle direction). In general, a dolphin shape is a very good one to imitate (to the extent possible).
Did you have a cold that day?
Sure did.
Kept hearing ‘Dirac Coefficient’
Are you from Dutch descent?
I was born in a small town near Antwerpen. (In the Flanders)
@@MichelvanBiezen Oh yeah i was thinking that later on that you could be from Belgium too. I'm from the south of the Netherlands (Noord Brabant), born and raised in a small town between Tilburg and Eindhoven.
I love Belgium, my mother was Flamish and my dad a Dutchman and sir you're doing a great job i love Physics.
I grew up in the small town of Kapellen, 4 km south of the Dutch border. I loved riding my bicycle into Holland to explore the countryside on their great bicycle paths. I had a great time at the science museum in Eindhoven. They are both beautiful countries with great people.