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Homework Help: Fluid Dynamics

  1. May 16, 2007 #1
    I am having a huge problem with understanding the derivation of velocity profiles for these type of problems. The one i am having the most difficulty is the flow of oil going down vertically along the surface of a glass rod. Where p=900 kg/m^3 and u=120 mPa's. How do I start this problem?
    Last edited: May 16, 2007
  2. jcsd
  3. May 20, 2007 #2
    here is the key

    Start by writing Navier-stokes equations in cylindrical coordinates.And make reasonable assumptions to simplify the equations. Like, 1 The flow is steady and two dimensional in r-z plane. Here z is the coordinate pointing downwards.You can also chose it to be pointing upwards. In both cases you should pay attention to the signs in the equations. 2 The flow is driven by gravational forces. 3 The shear forces on interface of oil and air are negligible. 4 The flow is in only z direction. Thus the r and θ velocities component go to zero.
    Now you need to do some integrations. Im leaving the rest to you...
    Good luck!
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