Results 1 to 4 of 4

Math Help - Fluid flow in pipe.

  1. #1
    Newbie
    Joined
    May 2010
    Posts
    1

    Smile Fluid flow in pipe.

    Hi,

    I have what I'm sure is an easy question for a maths genius. However I need to know the answer for an insurance claim:-

    "How much water in litres will flow through a 20mm pipe in one hour with the water pressure at 3 bar"

    Any answers will be much appreciated.

    Thank you

    welshman2010

    p.s. I hope I've posted this in the right section
    Follow Math Help Forum on Facebook and Google+

  2. #2
    Super Member
    Joined
    Mar 2010
    Posts
    981
    Thanks
    236
    You might be able to find a table somewhere that gives flow rates for pipes of various sizes and various pressures. Once you get that, you just have to convert the units.

    I think you need to know the length of the pipe. The water will flow more slowly through a longer pipe, right?

    If you can't find a flow rate online, I think it's possible to calculate it. You'd need someone who knows more about fluid dynamics than I do.

    - Hollywood
    Follow Math Help Forum on Facebook and Google+

  3. #3
    MHF Contributor
    Grandad's Avatar
    Joined
    Dec 2008
    From
    South Coast of England
    Posts
    2,570
    Thanks
    1
    Hello welshman2010

    Welcome to Math Help Forum!
    Quote Originally Posted by welshman2010 View Post
    Hi,

    I have what I'm sure is an easy question for a maths genius. However I need to know the answer for an insurance claim:-

    "How much water in litres will flow through a 20mm pipe in one hour with the water pressure at 3 bar"

    Any answers will be much appreciated.

    Thank you

    welshman2010

    p.s. I hope I've posted this in the right section
    The equation that gives the volume, V, of fluid flowing through a pipe in time t is:
    V = \frac{\pi P r^4 t}{8\eta l}
    where:
    P is the pressure difference between the ends of the pipe

    r is the radius of the pipe


    \eta is the viscosity of the fluid


    l is the length of the pipe

    This is known as Poiseulle's Law.

    So, you will need to know the length of the pipe and, to get an exact answer, the approximate temperature of the water (since this affects its viscosity).


    You need to use the correct units to get a sensible answer. In the case you mention:
    Pressure P=3 bar = 3\times 10^6 dynes per square cm

    r = 1 cm (assuming the 20 mm refers to the diameter of the pipe)


    t = 3600 seconds


    At 20^o C, \eta \approx 1\times 10^{-2} dyne-sec per square cm

    So I reckon that for a 1 metre length of pipe, this works out at about 4.2\times 10^8 \text{ cm}^3 =4.2\times 10^5 litres per hour.

    If you double the length of the pipe, you'll halve the rate of flow.


    Grandad
    Follow Math Help Forum on Facebook and Google+

  4. #4
    Super Member
    Joined
    Mar 2010
    Posts
    981
    Thanks
    236
    Thanks for stepping in with the formula I needed.

    - Hollywood
    Follow Math Help Forum on Facebook and Google+

Similar Math Help Forum Discussions

  1. [SOLVED] Fluid flow problem
    Posted in the Differential Equations Forum
    Replies: 9
    Last Post: September 27th 2011, 11:36 AM
  2. Bernoulli's Equation - Fluid Flow Problem
    Posted in the Differential Equations Forum
    Replies: 5
    Last Post: September 23rd 2011, 02:48 AM
  3. fluid flow
    Posted in the Advanced Applied Math Forum
    Replies: 1
    Last Post: June 5th 2011, 10:49 PM
  4. [SOLVED] Pipe flow from tank
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: May 19th 2010, 03:54 AM
  5. Fluid Flow:/
    Posted in the Math Topics Forum
    Replies: 0
    Last Post: October 28th 2009, 08:24 AM

Search Tags


/mathhelpforum @mathhelpforum