Rethinking how wastewater flows through rough drainage pipes
Mechanical Engineering PhD student, Aaron Kreji, specialises in experimental fluid mechanics, focusing on how surface roughness impacts turbulent flow in partially filled pipes found in drainage and wastewater pipe networks.
Aaron's research challenge
Addressing the lack of experimental data in how real-world wall roughness in partially filled pipes affects turbulence, secondary currents, and flow dynamics.
The top results
- Clear evidence of how wall roughness changes turbulence, secondary currents, and coherent flow structures in partially filled pipe flows.
- High-quality experimental data to support improved models of real drainage and wastewater pipes, where surface roughness, free-surface effects, and turbulent flow structures interact.
Behind the scenes
Aaron investigates how physical degradation and surface roughness impact water movement within partially filled drainage and wastewater systems. While traditional models rely on smooth pipe data, this study focuses on real-world conditions where age, corrosion, and deposits create turbulence and alter flow friction.
By examining secondary currents and turbulent structures, Aaron aims to fill a significant gap in experimental knowledge and data regarding infrastructure performance. These findings are intended to enhance flood risk management and improve the design and maintenance of essential utility networks. Ultimately, the work provides high-quality evidence to help engineers more accurately predict how water and pollutants move through deteriorating pipes.
Who benefits from this work?
The project can support those who work in industries and sectors involved in infrastructure management and environmental engineering. Particularly those involved in modelling, design, maintenance planning, and flood risk management of pipe systems and is specifically relevant for systems where ageing, deposits, and surface roughness have a serious impact on performance.
Aaron’s PhD research was funded by the Engineering and Physical Sciences Research Council (EPSRC) and Nuron Ltd, whose support enabled the experimental work presented in this study.
Research by Aaron Kreji
Rethinking how wastewater flows through rough drainage pipes
In Aaron’s words
Drainage and wastewater pipes run beneath almost every street, yet the flows inside them are still hard to predict under real conditions. Their surfaces roughen as they age and accumulate deposits, which affects friction, turbulence, mixing, and the movement of water and pollutants; conventional models represent this with a single roughness parameter in a friction relationship, which does not describe how the flow itself is organised. In the flows I have measured, the wall condition changes the turbulence and the slow currents circulating across the pipe, and by how much depends on how full the pipe is running. Those changes influence how much a pipe can carry and how sediment and pollutants are transported.
Aaron Kreji
PhD Researcher
Connect with Aaron on LinkedIn.