Does Pressure Multiplied by Volume and Volumetric Flow Rate Equal Force?

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SUMMARY

The discussion centers on the relationship between pressure, volume, and volumetric flow rate in calculating force. Participants clarify that the equation presented, which includes pressure (p), area (A), incremental length (delta L), and volumetric flow rate (dv/dt), is overly complex and combines multiple physical effects. The correct approach involves separating pressure effects from momentum change effects to avoid confusion. The units derived from the equation do not yield a straightforward force calculation, indicating a misunderstanding of the fundamental principles involved.

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  • Understanding of fluid dynamics concepts, particularly pressure and flow rate.
  • Familiarity with basic physics equations involving force and pressure.
  • Knowledge of dimensional analysis to verify unit consistency.
  • Experience with calculus, particularly integration in the context of fluid mechanics.
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  • Study the fundamentals of fluid dynamics, focusing on Bernoulli's equation.
  • Learn about the relationship between pressure and force in fluid systems.
  • Explore the concept of momentum change in flowing fluids and its implications.
  • Investigate dimensional analysis techniques to validate physical equations.
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Students and professionals in physics, engineering, and fluid mechanics who seek to deepen their understanding of the relationships between pressure, volume, and force in fluid systems.

FADFAD1
Does Pressure multiplied by volume multiplied by volumetric flow rate equal Force?
 
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FADFAD1 said:
Does Pressure multiplied by volume multiplied by volumetric flow rate equal Force?
Welcome to the PF. :smile:

What do the units work out as?
 
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berkeman said:
Welcome to the PF. :smile:

What do the units work out as?
N/m2 x m3 x m3/s so Nm4/s
 
FADFAD1 said:
x m3
Can you describe each term? It looks like you have an extra m^3 in there...?
 
the equation is pAdeltaL * dv/dt

so pressure times volume times change in length time volumetric flow rate
 
FADFAD1 said:
the equation is pAdeltaL * dv/dt

so pressure times volume times change in length time volumetric flow rate
The equation has pressure p.
Area A
Incremental length delta L
Incremental volume dv/dt

Are you not double-dipping? You have both area times incremental length and incremental volume?
 
In terms of a flowing fluid, there are multiple terms that contribute to force. One of them happens to be from pressure and looks like ##pA## (or rather ##\int p\;dA##). Your term has a bunch of extra stuff in it. My suspicion is that you are trying to combine too many physical effects into a single term rather than separating their contributions. Specifically, pressure effects and momentum change effects must be treated separately (though there are relationships between some of those variables).
 

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