Consider a small diffuse surface of area A1 = 1 cm2 with a total emissive power of 50000 W/m2. Another small surface of area A2 = 5 cm2 is located at a distance of r = 50 cm from A1 at an angle of θ1 = 60° w. r.t to the normal of A1. The line joining the two surfaces is at an angle of θ2 = 30° w. r.t to the normal of A2.

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)