Measurement and modeling of turbulent flow in water supply systems and its effect on contaminant transport

This paper describes the results of a measurement and modeling research project investigating the transport, accumulation and removal of contaminants from within water supply systems, including piping, fittings and fixtures. The traditional approach for decontaminating plumbing systems is to flush with water at high flow rates, primarily because this methodology is most easily implemented, and there are few simple alternatives. However, the effectiveness of this approach has not been demonstrated, and in fact, for several reasons this may not be the best way to remove contaminants. High velocity water flows in piping systems are in the turbulent regime, and the eddies that are generated may inhibit the transport and removal of entrained contaminants. This affects both the initial distribution and removal of contaminants. In the modeling component of this project, we investigated the movement of contaminants in pipe flows with obstructions representative of typical plumbing system fittings. This entails solutions of the equations for fluid flow, the solution of an advection-diffusion equation for the motion of the contaminants, and a boundary condition for the advection-diffusion model. The modeling results are compared to measurements conducted using real-world piping systems. The effect of turbulent flows on contaminant distribution and removal is evaluated and described.