Calculating Pressure Difference in Blood Flow Using Bernoulli's Equation

AI Thread Summary
The discussion focuses on calculating the pressure difference in blood flow using Bernoulli's equation, specifically between an artery and smaller veins. The user correctly determines the blood speed in the smaller veins to be 1.07 m/s and sets up the Bernoulli equation to find the pressure difference. However, they express confusion over the need for initial pressure values, which are not necessary since the difference in pressure can be calculated directly. Another participant argues that Bernoulli's equation is inappropriate for modeling blood flow due to its viscosity and suggests using Hagen-Poiseuille flow instead. The conversation highlights the complexities and limitations of applying Bernoulli's principle to biological systems like blood circulation.
GemmaN
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"An artery of radius 1 mm leaves the heart and travels upward 0.3 m to your shoulder, where it breaks into 3 smaller veins, each of radius 0.5 mm. Blood flows through the artery at a speed of 0.8 m/s as it leaves the heart. The density of blood is 1050 kg/m^3."
I determined that the blood moves at 1.07 m/s in the smaller veins, which is correct.

I am suppose to find the difference in pressure "between a point in the artery just as it leaves the heart and a point in one of the smaller veins just at the point where they split off"
I am pretty sure I am suppose to use bernoulli's Eqn.

P1 + d*g*y1 + 1/2 *d*v1^2 = P2 + d*g*y2 + 1/2 *d*v2^2
P1 + (1050 kg/m^3)(9.8 m/s^2)(0.3m) + (1/2)(1050kg/m^3)(0.8m/s)^2 = P2 + 0 + (1/2)(1050kg/m^3)(1.07m/s)^2

I have everything to use this equation, but the initial pressure. Am I missing a way to figure that out? I can't seem to get any of my pressure equations to work for this, P = F/A, P = P0 + dgh

The answer is suppose to be 3341 pascals
 
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The initial pressure is not needed. The difference in pressure is equal to (P2-P1), usually abbreviated as \Delta P.
 
What CRAZY individual thinks up an exercise where Bernoulli's equation is to be used on blood flow?

Blood is an extremely viscous fluid, and the arteries with so small radii, that any information gained from using Bernoulli's equation is guaranteed to be dead wrong.

At the very least, Hagen-Pousseille flow should be used as a base modelling tool (that's probably inaccurate as well).
 
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