Modelling of unsteady flow in siphonic roof harvesting system

Abstract

Siphonic roof drainage systems have been in existence for more than 40 years and are becoming an increasingly common element of urban drainage infrastructure. A siphonic system allows roof runoff to quickly reach its maximum flowrate. In contrast to a conventional system the siphonic approach to roof drainage aims to exclude air and to induce the full bore flow conditions required for siphonic action. This means that the filling and priming times are more efficient and quicker than for a conventional gravity-fed roof drainage system. Understanding the priming time of siphonic systems can help to identify potential problems in large systems that may not be able to fill and prime quickly enough to deal with high-intensity storms of short duration. The results from the work presented in this thesis will hopefully improve our understanding of the priming process in a siphonic roof drainage system and assist the water industry to move towards the use of unsteady flow models for design and performance modelling.