Can someone explain the theory behind the parabolic veloc. curve of laminar flow

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ilovelanguages

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This is my SDN disclaimer that this question is related to a physiology exam being taken at a medical school; it is not related to 'premed homework help'.


I'm studying CV dynamics, specifically laminar flow at this point. As this page explains, the velocity of perfectly laminar flow can be described by a parabolic curve.

To me, if we're talking about ideal flow, wouldn't everything move at the same speed? Every molecule would be traveling "straight", would have the same amount of neighboring molecules, and I don't see why they would not all have the same velocity.

I would really appreciate it if someone could explain to me why in ideal laminar flow there is greater velocity towards the middle of the vessel? Perhaps the assumption is that all resistance (or the vast majority of it) comes from the vessel walls, so distance away from wall leads to greater velocity?

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resistance (or the vast majority of it) comes from the vessel walls, so distance away from wall leads to less reduced velocity
this.

it actually says it on that page:
The orderly movement of adjacent layers of blood flow through a vessel helps to reduce energy losses in the flowing blood by minimizing viscous interactions between the adjacent layers of blood and the wall of the blood vessel.
 
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This is my SDN disclaimer that this question is related to a physiology exam being taken at a medical school; it is not related to 'premed homework help'.


I'm studying CV dynamics, specifically laminar flow at this point. As this page explains, the velocity of perfectly laminar flow can be described by a parabolic curve.

To me, if we're talking about ideal flow, wouldn't everything move at the same speed? Every molecule would be traveling "straight", would have the same amount of neighboring molecules, and I don't see why they would not all have the same velocity.

I would really appreciate it if someone could explain to me why in ideal laminar flow there is greater velocity towards the middle of the vessel? Perhaps the assumption is that all resistance (or the vast majority of it) comes from the vessel walls, so distance away from wall leads to greater velocity?

Here are a few links giving a very basic explanation. Remember that the models used are perfectly cylindrical, hard conduits and that arteries are more flexible and veins practically have only turbulent flow, due to valvules and very soft, shape-shifting walls.

General fluid dynamics:
http://www.efunda.com/formulae/fluids/overview.cfm

Flow types:
http://www.efm.leeds.ac.uk/CIVE/CIVE1400/Section4/laminar_turbulent.htm

and:
http://francesa.phy.cmich.edu/people//andy/physics110/book/Chapters/Chapter9.htm

The latter one comes from this site:
http://francesa.phy.cmich.edu/people//andy/physics110/book/Phy110.htm

Click on the links in the pages for a clearer picture.

Drink a couple of Red Bulls first.

Enjoy!
 
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