The investigation of fresh water pollution in pipe network due to water hammer

Milad Payesteh, Alireza Keramat, Masoud Anishosseini

Thursday 2 july 2015

11:15 - 11:30h at Asia (level 0)

Themes: (T) Hydro-environment, (ST) Impacts of pollutants on the water environment

Parallel session: 11G. Environment - Impact

This paper clarifies the possibility of fresh water pollution in pipe networks following a water hammer event. The water hammer phenomenon in a pipeline produces rapid changes in the fluid pressure which travel along the pipeline as a pressure wave. If e.g. the water hammer is generated due to an instantaneous valve closure of a downstream valve, the pressure wave transforms to rarefaction waves at moments after the half water hammer period. This negative pressure can suck materials from probable leaks on pipe into fresh water and pollutes it. The situation is worst especially when the pipeline is buried and the level of ground water is higher than the pipe elevation. This paper demonstrates as to how pollution can move from leaks into the pipeline due to water hammer and how it is mixed with fresh water and travels at different points of pipe by means of advection and diffusion mechanisms. To simulate this phenomenon, firstly, the water hammer equations are solved to predict the pressure and velocity distributions along the pipeline. These flow characteristics are then used to solve the advection-diffusion equation assuming some leaks as nodal boundary conditions. The simulation predicts the concentration of pollution at several points of the pipeline. The investigation is further extended to pipe networks. The results show the extent of pollution that spreads in pipe system from a leak with time progress after a water hammer event. Keywords: Water hammer, Advection - diffusion, water pollution, Transient flow