Fluid Mechanics: The Momentum Equation

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  • เผยแพร่เมื่อ 7 พ.ย. 2024

ความคิดเห็น • 34

  • @josephtraverso5355
    @josephtraverso5355 ปีที่แล้ว +2

    Well presented, thank you Caspar!

  • @Thookudhurai
    @Thookudhurai 2 วันที่ผ่านมา

    Let the the fluid has uniform flow throughout the pipe. Is that mean there is no momentum change in the pipe?

    • @CasparHewettFluids
      @CasparHewettFluids  วันที่ผ่านมา

      Yes, that is correct. Momentum is conserved.

  • @liambond3569
    @liambond3569 ปีที่แล้ว

    Would the vertical pressure force still be oriented downward if the curved pipe was facing down not up?

    • @CasparHewettFluids
      @CasparHewettFluids  ปีที่แล้ว

      No, the pressure force always acts inwards towards the control volume so it would be acting upwards if the pipe were facing downward.

  • @-HenguljyotiGayan
    @-HenguljyotiGayan ปีที่แล้ว +2

    Thanks a lot sir.

  • @kaursingh637
    @kaursingh637 5 หลายเดือนก่อน

    EXCELLENT-- WHICH UNIVERSITY ? -WHICH COUNTRY ?

    • @CasparHewettFluids
      @CasparHewettFluids  5 หลายเดือนก่อน

      Newcastle University, UK

    • @kaursingh637
      @kaursingh637 5 หลายเดือนก่อน +1

      @@CasparHewettFluids thank u sir

  • @pippakolking1998
    @pippakolking1998 2 ปีที่แล้ว +1

    How do we determine the direction of pressure force?

    • @CasparHewettFluids
      @CasparHewettFluids  2 ปีที่แล้ว +1

      We are considering the forces on the control volume, so the pressure force is acting inwards on that control volume (there is an equal and opposite pressure force outward, but that isn't relevant to the calculation) thus it is acting to the right on the left hand side and to the left on the right hand side.

  • @lightspd714
    @lightspd714 2 ปีที่แล้ว +2

    Why isn’t there a Q1 and Q2? In other words why can we assume that A1u1=A2u2=Q ?

  • @amanullahhayat8487
    @amanullahhayat8487 3 ปีที่แล้ว +3

    P2A2 and pQu2 have got opposite direction then why same sign (-)?? i mean why pQu2 have (+) mark??

    • @ghaithaq501
      @ghaithaq501 2 ปีที่แล้ว

      th-cam.com/channels/gnO_q7xjxSYotvyUMgwzEA.htmlvideos

    • @ronald_plus6
      @ronald_plus6 2 ปีที่แล้ว

      same question

    • @CasparHewettFluids
      @CasparHewettFluids  2 ปีที่แล้ว

      P2A2 is force due to pressure acting on the control volume while pQu2 is momentum out of the control volume

  • @mohsen9828
    @mohsen9828 ปีที่แล้ว

    if we consider a 90-degree bend pipe, with initial conditions as follows: inlet velocity 15 m/s, no change in cross-section area (let's say radius of 0.2 m), and we only know outlet pressure is equal to atmospheric pressure. Is Bernoulli's equation satisfied? does it mean outlet and inlet pressure are the same? in that case, there's no flow?!

    • @CasparHewettFluids
      @CasparHewettFluids  5 หลายเดือนก่อน

      Bernoulli equation is satisfied within the pipe so pressure will be constant if the pipe is horizontal, resulting in a jet at the outlet. The pressure in the pipe can't be atmospheric pressure if the water has a velocity! Conditions are different once water reaches the outlet. Thus, the problem you pose can't be solved. There is insufficient information. You would need to know the pressure in the pipe.

  • @ghbbllk4095
    @ghbbllk4095 7 หลายเดือนก่อน

    Why is the momentum force in the opposite direction as the pressure force? Seems like they would both be acting in the same direction, no?🤔

    • @CasparHewettFluids
      @CasparHewettFluids  7 หลายเดือนก่อน

      There are two elements of the momentum. The momentum into the control volume, which acts in the same direction as the pressure and the momentum out of the control volume which is in the opposite direction to the pressure

    • @CasparHewettFluids
      @CasparHewettFluids  7 หลายเดือนก่อน

      The pressure forces are those acting on the control volume, which is why they are both inward

  • @danielhakimzambri892
    @danielhakimzambri892 9 หลายเดือนก่อน

    Hello, what is ubar in the bousinesque equation

    • @danielhakimzambri892
      @danielhakimzambri892 9 หลายเดือนก่อน

      Is it like the average velocity or what?

    • @CasparHewettFluids
      @CasparHewettFluids  9 หลายเดือนก่อน +1

      @@danielhakimzambri892 yes, it is the average velocity 😉

    • @danielhakimzambri892
      @danielhakimzambri892 9 หลายเดือนก่อน

      @@CasparHewettFluids thanks

  • @punsthedisgrace
    @punsthedisgrace 3 ปีที่แล้ว +1

    is the momentum of a fluid equal to mass flow rate * velocity ???

    • @forresternick
      @forresternick 3 ปีที่แล้ว +1

      Mass * velocity = momentum, so mass/time * velocity = momentum/time, which just means that a change in momentum over time = a force :)

    • @forresternick
      @forresternick 3 ปีที่แล้ว +2

      You can verify this with the units: (kg/s)*(m/s) = (kg*m/s^2)

    • @ghaithaq501
      @ghaithaq501 2 ปีที่แล้ว

      th-cam.com/channels/gnO_q7xjxSYotvyUMgwzEA.htmlvideos

  • @blessingamosmatunya8908
    @blessingamosmatunya8908 2 ปีที่แล้ว

    On the summation of y direction forces, pQu is it not a negetive sir.

    • @CasparHewettFluids
      @CasparHewettFluids  2 ปีที่แล้ว

      If you mean in the example of the vertical bend you are correct, the outward momentum (not force) is in positive y direction, but you need to remember that for the momentum equation in the y-direction it is momentum out (i.e. is on the right hand side of the equation).

    • @mpt2878
      @mpt2878 ปีที่แล้ว

      ​@@CasparHewettFluids omg true