A Newtonian liquid, contained between two concentric, infinitely long, vertical cylinders of radii R1 and R2, where R2 > R1, is initially at rest. At time t=0+, the inner cylinder starts rotating about its axis with constant angular velocity Ω1.

(a) Specify the governing equation for this transient flow.

(b) Specify the boundary and the initial conditions.

(c) Calculate the velocity uθ(r, t).