A fluid with viscosity n fills the space between two long co-axial cylinders of radii R1 and R2, with R1 < R2. The inner cylinder is stationary while the outer one is rotated with a constant angular velocity w2. The fluid flow is laminar. Taking into account that the friction force acting on a unit area of a cylindrical surface of radius r is defined by the formula s = nr(dw/dr), find: (a) the angular velocity of the rotating fluid as a function of radius r; (b) the moment of the friction forces acting on a unit length of the outer cylinder.
Solution:
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