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Calculate the flow velocity

by supernova1387
Tags: bernoulli, fluid, velocity
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Jul7-13, 09:14 AM
P: 31
This might be simple but I can't remember how to do it.

problem: we have 2 tanks. One filled with atmospheric air at 1 bar and the other is vacuum. The two tanks are connected by a rigid pipe which has a valve. I open the valve and air flows to the vacuum tank. How do I calculate the air velocity?

P.s: I don't think Bernoulli is valid here because the flow isn't steady I guess. Please state your assumptions clearly.

Thanks in advance
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Jul7-13, 09:37 AM
Sci Advisor
P: 1,923
Flow velocity depends on the thickness and length of the pipe, and on the temperature of the air.
Jul7-13, 11:23 PM
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HW Helper
PF Gold
P: 6,546
Instead of 'thickness' of the pipe, the term 'internal diameter' would be more apt.

Jul7-13, 11:51 PM
PF Gold
boneh3ad's Avatar
P: 1,503
Calculate the flow velocity

Also pay attention to the pressures. The flow is going to start off choked but will eventually un-choke as the pressures equalize.

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