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Homework Help: Flow past a sphere

  1. Aug 11, 2009 #1
    1. The problem statement, all variables and given/known data
    Considering a unsteady, incompressible flow past a sphere placed in a channel. The sphere is offset somewhat from the center of the flow to destabilize what otherwise would be steady-state symmetrical flow. Calculate the tangencial rotational force at the sphere.

    2. Relevant equations

    3. The attempt at a solution
    My attempt is to make use of the Stoke's friction law for rotational motion of a sphere:
    [tex] F=-8 \pi \eta_0 a^3 \Omega [/tex]
    with [tex] \eta_0 [/tex] the viscosity, [tex] a [/tex] sphere radius, [tex] \Omega [/tex] sphere velocity.
    But this is the total force and I have to calculate only the tangencial.
  2. jcsd
  3. Aug 17, 2009 #2
    The friction force is a tangential force, then if I have to calculate the tangential rotational force, then I have only to calculate the friction force written above?
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