Numerical simulation of the dynamic operation of multi-outlet siphonic roof drainage systems

Although siphonic roof drainage systems have been installed in Europe since the 1970s, the design of such infrastructure is still based on steady state theory. Such approaches are only truly applicable at the design condition, under specific rainfall conditions, and cannot be used to assess the response of siphonic systems to alternative rainfall conditions and/or operational scenarios. Previous research at Heriot-Watt University led to the development of a numerical model capable of accurately simulating the performance of single outlet systems under a range of different conditions. The work reported herein details the logical extension to this work; i.e., the development of a numerical model to simulate the performance of multi-outlet siphonic roof drainage systems. The experimental work undertaken to assist in the development of the new model boundary conditions is briefly described, and relevant results are illustrated. The development of the numerical model is then detailed, and model output is presented. Finally, conclusions are drawn regarding the developed model, and plans for future work are outlined.