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Homework Help: Separation of Particles in a fluid flow?

  1. Jan 30, 2016 #1

    I'm doing some online research on fluid flow in waste water treatment. One of the problem I'm trying to find information about is how can visible particulate matter be separated within a liquid. I saw the following picture:


    What fluid concepts are going here that allow the grit to be separated (apart from gravitational forces)? Is the process related to turbulent flow?

    Any insight is really appreciated.

    Thank you.
  2. jcsd
  3. Jan 30, 2016 #2

    Simon Bridge

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    Same as how dirt swirls about in the sink when you wash your hands.
    The motion of the fluid pushes stuff around.
  4. Jan 30, 2016 #3
    So any turbulent motion can deposit debris around the surface of an object?
  5. Jan 31, 2016 #4

    Simon Bridge

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    Any motion in the fluid can shift particulate matter about. Circulation is famous for sorting particles though: see "panning for gold". Why would you expect otherwise with all the examples in Nature around you?
    In this case it's more that light particles stay in suspension longer because they are well light ... easier for the convection to lift.
    IRL the sludge at the bottom of a septic tank is not that nicely layered.
  6. Jan 31, 2016 #5


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    What is shown in your picture is some variety of vortex separator . The principle is well known .

    You say you have been doing an online search but couldn't find any information . Perhaps you are not using suitable keywords .

    Googling the obvious 'removing particulates from waste water' produces a large amount of information .

    Please come back if you have specific questions .
  7. Jan 31, 2016 #6
    Thank you Nidum! I googled vortex separator and got precise information about this subject!
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