Buckingham Pi Theorem - Heat and Mass Transfer - W7Q1

Using Buckingham Pi theorem, determine the dimensionless P parameters involved in the problem of determining pressure drop along a straight horizontal circular pipe. Assuming the pipe is a smooth pipe. Relevant flow parameters: pressure drop (ΔP), density (ρ), average velocity (u), viscosity (μ), pipe length (L), pipe diameter (D).
1) How many dimensionless numbers (Pi groups) describe the problem?
2) Write the equations for these dimensionless numbers;
3) What are their physical significance.