A water treatment plant processes 30,000 cubic meters of water each day. A square rapid-mix tank with vertical baffles and flat impeller blades will be used. The design detention time and velocity gradient are 30 seconds and 900 s-1 Determine the power input, if the temperature of the water is 20°C. µ = 1 x 10-3 kg/m•s. 1kW = 1000 J/s, 1J = 1N•m = 1 kg•m2/s2. Note: you can use the equation in its current version.

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)