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Homework Help: Rayleigh Problem

  1. Oct 20, 2009 #1
    1. The problem statement, all variables and given/known data
    Consider the Rayleigh problem, but allow the plate velocity to be a function of time, V(t). By differentiation show that the shear stress, tau = du/dy*absolute viscosity, obeys the same diffusion equation that the velocity does. Suppose that the plate is moved in such a way as to produce a constant surface shear stress. What are the velocity profile and the surface velocity for this motion.

    2. Relevant equations
    I'm not sure that these are actually relavant but here is what I assume:

    Shear Stress = - Absolute Viscosity*V0 / SQRT(PI *kinematic viscosity*t)

    density*dv/dt = absolute viscosity*d^2v/dy^2 => simplified momentum eqn.

    3. The attempt at a solution
    I'm not sure how to even get started on this problem. Any suggestions or help would be appreciated. Thanks
  2. jcsd
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