Question about Poisseuille's law and blood flow

[don_anon25]

I know that rate of flow is equal to pi*(P1-P2)*R^4/8nL. For blood in the coronary artery, I know the pressure drop, and the radius of the artery. What is the viscosity of blood? I can't find this value anywhere! And what value should I enter for L (distance L along a tube)? Is there an actual value somewhere for the length of the coronary artery in mm?

 

[FredGarvin]

According to this source http://www.usc.edu/dept/biomed/bme403/Section_3/viscosity_of_blood.html
The value is approximately three times that of water. So if I use the dynamic viscosity of water at 20°C as
$$\mu_{water} = 20.92 \frac{Lb_f sec}{ft^2}$$, that would mean that $$\mu_{blood} = 3.0 \mu_{water}$$ so...

$$\mu_{blood}= 62.76 \frac{Lb_f sec}{ft^2}$$

$$\mu_{blood}= 3.0 x 10^6 cP$$

I can't really help you in terms of L in your equation. A couple of options would be to a)Leave L blank and express your answers in flow per unit length (which sounds kind of funny but is technically correct). or b)Make an estimation.

 

[charng]

Thank you for your question. The viscosity of blood can vary depending on factors such as temperature, hematocrit (percentage of red blood cells in blood), and shear rate. According to a study published in the Journal of Clinical Investigation, the viscosity of human blood ranges from 3.5 to 4.5 cP (centipoise) at a shear rate of 100 s-1. However, this value may vary in different individuals and under different conditions.

As for the distance L along a tube, this refers to the length of the artery through which the blood is flowing. The length of the coronary artery can vary from person to person, but on average, it is around 20-30 mm. However, it is important to note that the length of the artery may change depending on factors such as age, disease, and vessel dilation.

In summary, the viscosity of blood and the length of the coronary artery may vary, but you can use the average values mentioned above in your calculations for Poisseuille's law. Additionally, it is always best to consult multiple sources and consider the specific conditions of your experiment when determining these values. I hope this helps.