The velocity distribution for water (20°C) near a wall is given by u = a(y/b)1/6, where a =10 m/s, b=2 mm, and y is the distance from the wall in mm. Determine the shear stress in the water at y 1= mm.

Amixture of slurry and mud is to be pumped through a horizontal pipe of diameter 500 mm. the fluid behaves as a bingham plastic with a yield stress of 30 pa and viscosity 0.04 pa. s. describe the effects of the shear stress through a transverse section of the pipe by plotting the variation in shear stress and velocity profile: (i) just before the slurry starts to move (ii) as the slurry flows when the pressure gradient is double that in part (i)