Physics 34 Fluid Dynamics (13 of 24) Viscosity & Fluid Flow: Laminar Flow Between Plates

[@michaelrudert3406]

Clean and understandable made. Thank you for this explaination!

[@MichelvanBiezen]

Glad it was helpful!

[@MichelvanBiezen]

Mark, The equations are correct as stated.

[@jacksondoorbar9769]

Michel,Could you explain why a force must be applied to the bottom plate to keep it stationary? In my mind, I imagine when you move the top plate that the bottom plate wont move as the velocity of the fluid there is zero. I can't figure out why a force would need to be provided to keep the bottom plate stationary and why this force would be equal to the force applied to the top plate. Doesn't this mean that if you did not apply that force to the bottom plate, by applying force to the top plate you would cause an equal force to the right on the bottom plate. Any assistance in my confusion would be greatly appreciated.

[@MichelvanBiezen]

Excellent question. If the bottom did move then the fluid above the bottom plate would move as well. Since the bottom layer of fluid does not move it must be kept in place by the bottom, since the layer above the non-moving layer is moving and pulling on the non-moving layer. Thus the bottom layer of fluid pulls on the bottom and thus the bottom must be kept in place.

[@979best]

doctor michel ... i have question please . each layer of fluids consider as one plate, isn't it ?

[@tou786786d]

Very good explanation.....thank you very much may god bless you

[@TheOnlyEsc2]

Can you give intuition why stress is F/A in both cases? I can see that the upper plate tries to "leave" the plates below it and thus there is pressure on them, but why it is exactly this pressure? Why the force uniformly distributes in all directions?

[@samooi1860]

i see you might be unfamiliar with sheer stress. I suggest you get acquainted with that first.

[@muhammadsaqibirshadmuhamma1955]

Can anyone tell if there are three plates instead of two and fluid is in between these plates having different viscosity? If the upper and middle plate is moveable and the bottom plate is stationary, with what velocity middle plate will move if we move the upper plate with velocity v? consider plates are weightless

[@tolgahan5027]

Sir will you make videos about head losses ,losses due to friction , moody diagram and sudden expansion in pipes? i hope you are planning to make soon

[@MichelvanBiezen]

That is part of the plan, but we are working on many other topics at the moment.

[@sroydetroy6404]

I would be grateful if someone can explain why is delta distance( difference of distance between the lower and upper regions) is equal to TIME times the velocity of liquid in the upper region- Like why is time even a factor here?

[@MichelvanBiezen]

This is using the concept: distance = velocity x time

[@rever4217]

What if the object was accelerating instead of having uniform velocity? Since the velocity isn't uniform does this mean the force acting on it changes as well with time?

[@MichelvanBiezen]

According to Newton's second law: F = m dv/dt which means that a constant force causes a change in velocity.

[@rever4217]

But the acceleration here is 0 yet there is a force. Using that equation F would equal 0. I'm talking about the one in the video where tau = F/A = miu x dV/dy. If the block is accelerating how do you use this equation to find out the force? Edit: Oh wait, scratch that. So you just use the basic F = ma in that case to determine the force if it's accelerating? That makes more sense. That's right right?

[@thexman5856]

Hi Michael 😀 this is some very Well explained videos you are showing, thumbs up 👍 i was looking for a video or tutorial of calculating the flow between to parallel pipes, perhaps done by the Hardy cross methoed, would that be possible, regards

[@conradnehemiah7978]

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[@damaridamien4999]

@Conrad Nehemiah instablaster ;)

[@conradnehemiah7978]

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[@conradnehemiah7978]

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[@damaridamien4999]

@Conrad Nehemiah happy to help :)

[@orangejuiceearrape]

This was a helpful video, thank you for posting this.

[@jacksondoorbar9769]

Also, does the viscosity affect how the force applied translates into the velocity of the plate? I was thinking if you kept A and L the same and changed the viscosity of the fluid, how would the velocity and the force change?

[@MichelvanBiezen]

If the viscosity is increased, then to obtain the same velocity of the fluid, it would require increased force proportionally. Double the viscosity and you will need twice the force in order to maintain the fluid velocity.

[@tomatrix7525]

So clear

[@ahmadeldesokey9844]

Sir , is the resultant force on the above plate is zero since it is moving with constant velocity ?

[@MichelvanBiezen]

There is no net force on the top plate if a force pulls on it with constant velocity.

[@ahmadeldesokey9844]

@@MichelvanBiezen thanks

[@roaahedaya1779]

could you please tell the difference between laminar flow and turbulent flow? Thanks in advanve

[@MichelvanBiezen]

Laminar flow is basically where all the molecules in the fluid travel in the same direction. Turbulent flow is where the general movement is in the same direction, but there are pockets within the fluid where the flow is in a different (and erratic) direction causing the resistance to the flow to increase.

[@negargh4208]

Thanks .it was clear to understand

[@ibrahimmagdy827]

may god bless you

[@ysdesigns6763]

thank you...

[@SentientTent]

a fair bit better than my teacher.

[@amanpandey7035]

🙌🙌 Thank you

[@vihangatharusha5488]

good explain

[@noname-ic5mx]

good explanation thank you

[@mohamedhassanin6054]

you're amazing . Thank you

[@katiesunghee919]

life saver

[@None0fY0urConcern]

@mark

[@MichelvanBiezen]

?

[@allankardecdealmeidajunior4096]

You have the Richard Feynman's accent.

[@ahnafshan1225]

Great

[@janayool1001]

are you professor ?

[@MichelvanBiezen]

+jana yool Yes

[@janayool1001]

I have problem about fluid dynamic 2 different ways you used In the first you have used 3 forces and in the second you have used 4 forces which one is the true?

[@janayool1001]

Buoyancy viscosity, and drag forces