Experimental and numerical investigation of interactions between above and below ground drainage systems

Abstract

This paper presents the results of the experimental and numerical investigation of interactions between surface flood flow in urban areas and the flow in below ground drainage systems (sewer pipes and manholes). An experimental rig has been set up at the Water Engineering Laboratory at the University of Sheffield. It consists of a full scale gully structure with inlet grating, which connects the 8 m(2) surface area with the pipe underneath that can function as an outfall and is also further connected to a tank so that it can come under surcharging conditions and cause outflow from the gully. A three-dimensional CFD (Computational Fluid Dynamics) model has been set up to investigate the hydraulic performance of this type of gully inlet during the interactions between surface flood flow and surcharged pipe flow. Preliminary results show that the numerical model can replicate various complex 3D flow features observed in laboratory conditions. This agreement is overall better in the case of water entering the gully than for the outflow conditions. The influence of the surface transverse slope on flow characteristics has been demonstrated. It is shown that re-circulation zones can form downstream from the gully. The number and size of these zones is influenced by the transverse terrain slope.

Assessment of the Ability of a Volume of Fluid Model to Reproduce the Efficiency of a Continuous Transverse Gully with Grate

“…This value is in-line with other researchers work on gullies (Djordjević, et al, 2013) that also 182 used such fine meshes to model urban drainage devices. Extrapolating this edge size to the 183 full domain, the total number of cells can quickly rise to approximately 45 million of cells.…”

Quantification of energy losses at a surcharging manhole

“…This is within the range that might be expected for a shallow water running over an urban surface during a lood event, and is similar to the range used by (Djordjevic et al 2013) for the physical modelling of gully performance during lood events.…”

Modelação hidráulica e de qualidade da água dos sistemas de drenagem em meios urbanos

“…et al conduziram a um aperfeiçoamento dos modelos de drenagem urbana existentes (DJORDJEVIĆ et al, 1999;HSU et al, 2000;DJORDJEVIĆ et al, 2005;MAKSIMOVIĆ et al, 2009;SIMÕES, 2012;BAZIN et al, 2013;DJORDJEVIĆ et al, 2013). Dessa forma, desenvolveu-se o conceito de drenagem dual, em que o escoamento superficial é simulado por meio de um sistema constituído por canais abertos e bacias (sistema principal), que, por sua vez, está ligado ao sistema de coletores (sistema secundário) (PRICE & VOJINOVIĆ, 2011).…”