Energy dissipation by jet diffusion in stormwater drop shafts

This paper considers energy dissipation by jet diffusion in drop shafts used in urban stormwater systems, using the theory of circular turbulent jets. It presents experimental results on the decay of the maximum velocity in the jet for D/d in the range of 5 to 15, where D is the diameter of the chamber and d is the diameter of the jet at the water surface in the diffusion chamber. It was found that when D/d is small [Formula: see text], the decay of the velocity in the jet is appreciably larger than that in a jet in a large stagnant ambient. Key words: jet diffusion, drop shafts, stormwater systems, turbulent flow.