Pressure difference in a horizontal constant area pipe

AI Thread Summary
The discussion centers on the pressure difference in a horizontal pipe with constant area, questioning the applicability of Bernoulli's equation under non-steady state conditions. Key points include the conservation of mass flow and the influence of friction on velocity and pressure. The participants clarify that while mass flow must remain constant, friction leads to head loss and a decrease in pressure, impacting the overall energy balance. The confusion arises from assumptions about flow conditions and the effects of viscosity. Understanding these principles is essential for solving the problem accurately.
Blitz12345
Messages
2
Reaction score
0

Homework Statement



see attachment

Homework Equations


not sure if these are applicable because i don't think its steady state anymore
mass flow in=mass flow out
sum of forces in x direction= rate of momentum in-rate of momentum out
bernoulli's p+0.5ρ(v^2)= constant

The Attempt at a Solution


2.2a No
2.2b true, true, false as bernoullis assumption states inviscid flow, true if the given equations are true, true as the fluid is slowing down so resultant force is going in the left so pressure force at 2 is greater then pressure 1.
I am confused on making the correct assumptions could someone help me please?
 

Attachments

  • Fluid mech question.png
    Fluid mech question.png
    11.8 KB · Views: 490
Physics news on Phys.org
2B is false. The amount of liquid entering the pipe has to be equal to the amount of liquid exiting it in steady operation. Friction won't cause a decrease in velocity (at the wall the liquid isn't moving anyway for viscous fluids). The friction will cause a head loss though. So you see the impact in a decrease in pressure This energy is converted into heat. Maybe now you can get the other parts as well?
 
Back
Top