A long, round wire with radius a is pulled at a constant speed Uo through a long, round tube of radius b along its centerline. The tube is filled with a viscous fluid with constant density p and viscosity . Assume that the flow is laminar and fully developed with d = 0 (where z is the coordinate along the tube axis), and that uz = uz (r) only. (a) (b) (c) Find the velocity profile u (r). What is the force per unit length required to maintain the motion of the wire? Consider now the situation where b and the fluid and wire are initially at rest. At time t = 0, the wire is impulsively moved to the right at a constant velocity Uo. Write out the appropriate equation of motion for this case, as well as the necessary boundary and initial conditions. Can you apply a similarity solution to solve this problem? Why or why not? 26 , 2a Uo