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Homework Help: Pressure change when volume changes for incompressible fluid

  1. Jan 26, 2015 #1
    1. The problem statement, all variables and given/known data

    Hi guys,

    My first post here, I hope someone can help me out with a quick fluid mechanics problem.

    I'm looking to calculate the pressure increase inside a closed tube full of water when the tube is crushed and therefore its volume reduced.

    The tube is filled completely with water and pressurised to a nominal pressure of 10 bar. The starting volume is 2.1l and the volume after crushing is 90% of the initial volume.

    2. The relevant equations

    The tube remains sealed at all times so I think I can consider the fluid to be static and as its water, incompressible. However im struggling to find the relevant equation to allow me to calculate the new pressure. All the static problems i have seen are concerned with open containers.

    Can anyone help?


  2. jcsd
  3. Jan 26, 2015 #2
    Look up the BULK COMPRESSIBILITY of water. But a 10% decrease in volume seems very unlikely.

  4. Jan 26, 2015 #3
    Ok thanks, so i can rearrange to solve for dP using the values i quoted above?

    Sorry i should probably explained more thoroughly, I am crushing the tube with a press into a machined die as part of a hydroforming operation, the 10% is a rough approximation using the shape of the die as an indication of the form the tube will take.


  5. Jan 26, 2015 #4
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