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Q & A: Flux through half full airtight container vs. pressure?

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Most recent answer: 12/11/2015
Q:
Let's say I have an airtight container half full with some liquid. On one of the sides somewhere near the bottom I have an input from where fluid is constantly coming in, and at the bottom I have an output where fluid is constantly going out (let's say at the say rate). My question is, if I increase the air pressure in the container, it will remain constant?
- Balint Cristian (age 27)
Budapest, Hungary
A:

The initial state is a steady-state in which each incoming fluid element increases the pressure, whereas efflux releases this build-up. If you increase the air pressure, the system response will relax towards the equilibirum. You would observe a sudden jump in the efflux rate, which gradually decays to the equilibirum level because the volume of the air will increase meaning pressure will decrease once again.

You can achieve this perturbation either by an external pump or by simply increasing the influx so that the air volume decreases hence increasing its pressure. If you go for the former case and maintain a constant high pressure, then you can eventually drain the whole fluid completely.

Tunc


(published on 12/11/2015)

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