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How do I calculate the yield pressure for a Bingham plastic in a tube?

  1. Dec 28, 2016 #1
    I have three questions.
    1. How do I calculate the yield pressure for a Bingham plastic in a tube if I am given:
    Length of tube
    Diameter of tube
    Yield stress of liquid

    2. Is it possible to engineer a liquid to have a specific yield stress ?
    3. What kind of material would be suited for engineering a specific yield stress? Could it be done with silicon oils or could it be done with additives to water?
  2. jcsd
  3. Dec 28, 2016 #2
    I don't quite understand your first question. Are you asking how much of a pressure difference is required before the bingham plastic begins to flow?
  4. Dec 28, 2016 #3
    Yes I am asking how much pressure difference is required for flow. I think that I have read somewhere that a larger initial pressure is required for small diameters.
  5. Dec 29, 2016 #4
    Hi Chester
    You already answered the first question for me. I was googeling yield pressure and getting nothing. The right words were the ones you used in your reply to me:)
    I still need answers for the two last questions.
    The formula is:
    Found in this PDF
  6. Dec 29, 2016 #5
    Nicely done. For questions 2 and 3, I recommend that you google Bingham plastics and dilatent fluids and see what you come up with.
  7. Dec 29, 2016 #6
    Hi Chester

    I have already been googeling for hours on question 2 and 3 but the only thing that comes up is general stuff about ketchup or specific stuff about solving the governing equations or simulations. I have so far been unable to find a nice catalogue from a supplier producing a liquid with the desired yield stress or a company claiming to be able to make tailor made liquids with the desired properties. I have not been able to find a chemical formulation of a liquid with at attached yield stress number at all. I am looking for a liquid with a yield stress in the range of 150 Pa to 250 Pa with as low a viscosity as possible or maybe even a shear thinning liquid. The liquid can not be a suspension.
  8. Dec 29, 2016 #7
    Ugh. Most Bingham plastics are typically going to be suspensions. I was thinking of something like drilling mud, which is a suspension of bentonite clay particles. You need to find something that forms a gel, so maybe something with polar molecules with ends that attract. Unfortunately, this is about all that I can help. I don't know much more.
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