A flat disk with a central opening of diameter D , is set across a pipe

A flat disk with a central opening of diameter D_ᵒ, is set across a pipe of diameter D, and the pressure drop Δp across the opening is measured. It is postulated that Δp is a function of the average fluid velocity in the pipe V̅, the density of the fluid ρ, the fluid viscosity μ, and the diameters of the pipe and the opening, D and D_ᵒ, respectively. Thus Δp = Φ(V̅, ρ, μ, D, D_ᵒ)

Find an acceptable set of dimensionless groups which relate these various factors.