Problems from Middleman's book:
4. Additional questions about the oil-water lubricated flow problem.
a. What is the physical reason that additional oil flow is possible if the water layer is increased until about 30% of the radius?
b. Why do you get a separate equation for the velocity field for each phase?
c. What are the two boundary conditions at the interface of the oil and water?
d. Explain how to find the maximum enhancement in oil flow that is possible for a given oil viscosity
e. If the density of the oil and water are not identical, will this scheme work?
f. Explain why increasing the flow rate in a single phase, incompressible flow always leads to a higher pressure drop and but does not for this example.