A1/10th scale model of an airplane is to be tested in a wind tunnel that operates with air at a pressure of 20 atmospheres. the plane is expected to fly at a speed of 500 [km/hr]. (a) what speed should the wind tunnel be run? (b) if the drag measured on the model is 337.5 [n], what is the corresponding drag on the full size airplane? recall that the viscosity is effectively independent upon pressure changes.

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)