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Homework Help: Laminar flow in pipe

  1. Apr 20, 2016 #1
    1. The problem statement, all variables and given/known data
    why the shaer stress ( tau) formula is given by μ(dv/ dy ) = μ(-dV / dR) , why there is a negative sign there ?

    2. Relevant equations


    3. The attempt at a solution
     

    Attached Files:

  2. jcsd
  3. Apr 21, 2016 #2
    The negative sign is included because you are considering the velocity as a function of the distance from the center line of the pipe, not from the wall.
     
  4. Apr 21, 2016 #3
    why when we are considering the velocity as a function of the distance from the the wall , it's positive ? or we can also consider the distance from the wall as positive ?
     
  5. Apr 24, 2016 #4
    can we consider the distance from the centerline of pipe to wall as positive ?
     
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