TBR: Blood Turbulent Flow

[justadream]

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TBR Bio Book I page 117 #26



“During circulation of the blood, turbulent flow could increase with a decrease in the ___”



Answer: Viscosity (I agree)



Another choice that was wrong: diameter of the blood vessels



In a previous thread, @Cawolf helped me understand how it is that when diameter decreases by a factor of 2, the velocity increases by a factor of 4 (this is also seen in Wikipremed’s physics flashcard #186)



Reynolds: rho*v*r / viscosity



Thus, plugging into Reynold’s: 4 * .5 = 2

The Reynolds number INCREASES so turbulence should increase.



Did TBR overlook this or is there something special about the unideal fluid flow in the circulatory system that constitutes an exception*?



*However, I’m pretty sure Wikipremed’s flashcard #186 was applied to the circulatory system as well.

 

[Cawolf]

I would assume that in these questions they are just looking at an isolated change.

So though technically you are correct, I would take these questions as how isolated changes effect the fluid flow.

So if we are looking at isolated changes, a decreased diameter would result in more laminar flow.