Does Poiseuille's Law apply for vertical motion of fluids down a tube?

In summary, the conversation revolved around investigating the flow rate of different dilutions of glycerol through an orifice in a vertical tube. The individual was looking for a way to quantify the results and sought advice on whether Poiseuille's Law applied to vertical fluid motion. They also questioned the proportional relationship between viscosity and glycerol fraction and were referred to a website for assistance. Ultimately, they were able to improve their graph with the help of the information provided.
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I investigated the flow rate of differing dilutions of glycerol through an orifice of a vertical tube and obtained the following:
1625006338200.png

I'm looking for a way to quantify these results so looked to Poiseuille's Law;
Screenshot 2021-06-29 at 23.40.27.png

I'm pretty sure my graph does not show inverse proportion? Could anyone advise me as to where I've gone wrong / if there is another law governing this relationship - does Poiseuille's Law apply for the vertical motion of fluids?
 
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  • #3
haruspex said:
What makes you think the viscosity will be proportional to the fraction that's glycerol?
See if http://www.met.reading.ac.uk/~sws04cdw/viscosity_calc.html helps.
I see. I've got a much better looking graph now. Thanks a lot :)
 

1. What is Poiseuille's Law?

Poiseuille's Law is a scientific principle that describes the flow of fluids through a tube or pipe. It states that the rate of flow is directly proportional to the pressure difference between the two ends of the tube, and inversely proportional to the length and viscosity of the fluid.

2. Does Poiseuille's Law apply to all types of fluids?

Yes, Poiseuille's Law applies to all types of fluids, including liquids and gases. However, it is most commonly used to describe the flow of incompressible fluids, such as water or oil.

3. Can Poiseuille's Law be applied to vertical motion of fluids?

Yes, Poiseuille's Law can be applied to both horizontal and vertical motion of fluids. However, the calculations may differ slightly due to the effects of gravity on the vertical motion.

4. How does temperature affect Poiseuille's Law?

According to Poiseuille's Law, the viscosity of a fluid is directly proportional to its temperature. This means that as the temperature increases, the viscosity decreases and the flow rate increases.

5. Are there any limitations to Poiseuille's Law?

While Poiseuille's Law is a useful principle for describing fluid flow, it does have some limitations. It assumes laminar flow (smooth and orderly), and does not account for turbulence or compressibility of fluids. Additionally, it may not accurately predict flow in very narrow or very wide tubes.

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