We are looking at the top with the origin in the middle, so we are evaluating at y = h/2. When we plug in our values (make sure to use correct units), h is still the distance between plates. y = 0 is the middle between the two plates, where the velocity, U, is a maximum.
I hope you feel happy after hearing that finally, I looked up in the 12-grade book because I totally forgot derivative formula which caused me a headache for the whole day as well as search.
Thanks for the great video (along with the others in the Fluid Mechanics playlist). Do you have citable sources for the the two equations presented in this video?
how did you get tow to equal 1.83 when i am doing the problem i keep getting .001824, I am not sure if I am plugging a number in wrong but is the equation( 4 (1.14*10^-3)(0.1))/.25
In the lower plate shouldn´t the shear stress be in the same direction that in the upper one? Cause, I think that always the shear stress is in oposite direction to the velocity and decreases while the velocity grows so it would be zero at the origin and have both maximum values (negative to the velocity) near the plates. I would realy appreciate that you answer my question. Greetings
This is a tricky concept. Since here our origin is the middle between the plates, the shear stress has to be relative to this. So when we use a positive direction (up), the shear stress is in the negative direction. When we use a negative direction (down) the shear stress is in a positive direction. This is all because of the origin (shear stress is directional). If you made the bottom plate the origin and evaluated at 0 and h for the top plate, what happens? In reality since the fluid is flowing to the right due to a pressure difference driving force...the shear stress acting on the fluid from the walls is to the left, slowing the fluid down near the walls. Try to approach it from the idea that its dependent on perception and your coordinate system origin.
If y = h then shear stress would -3.66 N/m^2 and y = 0, shear stress would be 0. But, I am having trouble finding for what value of y is umax, maximum.
We are looking at the top with the origin in the middle, so we are evaluating at y = h/2. When we plug in our values (make sure to use correct units), h is still the distance between plates. y = 0 is the middle between the two plates, where the velocity, U, is a maximum.
Make sure to have correct units...0.25 mm and 1.14x10^-3 has meters.
This channel is amazing. you totally saved my ass on two CHE finals bro. keep up the good work.
This screencast has been reviewed by faculty from other academic institutions.
I hope you feel happy after hearing that finally, I looked up in the 12-grade book because I totally forgot derivative formula which caused me a headache for the whole day as well as search.
Thanks for the great video (along with the others in the Fluid Mechanics playlist). Do you have citable sources for the the two equations presented in this video?
how did you get tow to equal 1.83 when i am doing the problem i keep getting .001824, I am not sure if I am plugging a number in wrong but is the equation( 4 (1.14*10^-3)(0.1))/.25
if the question ask about the shears stress for both plates. are we have to sum the answer or leave it for two answer?
Since the final value is negative (-1.83), the direction in the plus x direction. Therefore you made a mistake in the end, please correct that.
why is the derivative mulitplied by 2 at the end? shouldnt it just be 4y/d^2
In the lower plate shouldn´t the shear stress be in the same direction that in the upper one? Cause, I think that always the shear stress is in oposite direction to the velocity and decreases while the velocity grows so it would be zero at the origin and have both maximum values (negative to the velocity) near the plates. I would realy appreciate that you answer my question. Greetings
This is a tricky concept. Since here our origin is the middle between the plates, the shear stress has to be relative to this. So when we use a positive direction (up), the shear stress is in the negative direction. When we use a negative direction (down) the shear stress is in a positive direction. This is all because of the origin (shear stress is directional). If you made the bottom plate the origin and evaluated at 0 and h for the top plate, what happens? In reality since the fluid is flowing to the right due to a pressure difference driving force...the shear stress acting on the fluid from the walls is to the left, slowing the fluid down near the walls. Try to approach it from the idea that its dependent on perception and your coordinate system origin.
If y = h then shear stress would -3.66 N/m^2 and y = 0, shear stress would be 0. But, I am having trouble finding for what value of y is umax, maximum.
what is y?
great video!
thankyou :)