Velocity in a circular orifice

Use Buckingham’s π theorem to show that the velocity of fluid flow through a circular orifice is given by the following equation: v= √(2gH ) φ [D/H, μ/ρvH] Where, v is the velocity, g is the acceleration due to gravity, H is the head causing the flow, D the diameter, μ and ρ are the co-efficient of dynamic viscosity and the density of the fluid. Express v as a function of H, D, µ, ρ and g