Athin walled tube is carrying hydrogen gas at a concentration of 3 kg/m^3. if the pipe wall is 6 mm thick and the diffusivity of hydrogen in the pipe material is 4.5x10^-5 m^2/s. a. what is the rate of loss (flux) of hydrogen to the outside atmosphere by diffusion through the wall? b. how much hydrogen will escape in 24 hours if the pipe is 21mm in diameter and 24 meters long?

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)