Poiseuille's principle vs flow rate continuity equation

[xsoppy]

I'm confused with how according to the poiseuille's equation as you increase the radius the flow rate also increases, but according to Q = A1v1 = A2v2 the avg speed and area on each side should be inverse


Maybe I'm misunderstanding the difference between Q and v? Or does poiseuille's not apply when the area of the pipe changes?

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[hebrewBAMmer]

I'm confused with how according to the poiseuille's equation as you increase the radius the flow rate also increases, but according to Q = A1v1 = A2v2 the avg speed and area on each side should be inverse


Maybe I'm misunderstanding the difference between Q and v? Or does poiseuille's not apply when the area of the pipe changes?

Q is the flow rate, i.e. how much volume flows through a pipe per unit of time. v on the other hand is measuring the speed at which particles of fluid move through (not a volume but just a speed). As you can imagine, if you have fluid moving faster through a pipe, you expect more fluid to go through per unit time, hence when v increases, so does Q.

What happens when I expand the radius of my pipe? There's much more area for my fluid to flow through, hence Q increases (as seen in Poiseuille's law).

Furthermore, try reading through this and see if it clears things up: Fluid Dynamics - Continuity vs Poiseuille

 

[xsoppy]

Q is the flow rate, i.e. how much volume flows through a pipe per unit of time. v on the other hand is measuring the speed at which particles of fluid move through (not a volume but just a speed). As you can imagine, if you have fluid moving faster through a pipe, you expect more fluid to go through per unit time, hence when v increases, so does Q.

What happens when I expand the radius of my pipe? There's much more area for my fluid to flow through, hence Q increases (as seen in Poiseuille's law).

Furthermore, try reading through this and see if it clears things up: Fluid Dynamics - Continuity vs Poiseuille

That cleared it up a lot thank you