Fluid flow through a pipe - Conservation of mass and/or momentum?

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SUMMARY

The discussion focuses on the principles of fluid dynamics, specifically the conservation of mass and momentum in a nozzle scenario. The user calculated the density of air at the inlet and outlet and applied the conservation of momentum, resulting in a value of 1004, which differed from the expected 1060. The discrepancy arises because while mass flow remains constant, the nozzle accelerates the fluid, leading to increased velocity and decreased density, thus validating the conservation of mass over momentum in this context.

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  • Basic calculations involving density and velocity
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theBEAST
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Homework Statement


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The Attempt at a Solution


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So first I found the density of the air coming in and going out. Next I used conservation of momentum with two forces caused by the pressures at the entrance and the exit of the nozzle.

I end up getting 1004 which is not the same as 1060. If I just use conservation of mass so ρVAout=ρVAin I get exactly 1060. So why is it that conservation of momentum does not work in this scenario?
 
Physics news on Phys.org
The nozzle is accelerating the flow of the fluid through the restriction. The mass flow into the nozzle is the same as the mass flow out, but the velocity has increased while the density decreases.
 

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