School of Civil Engineering

Below are the 6 major research topics:

Open Channel Flow and Hydraulic Structures

Open channel flows are encountered in a wide range of applications from large rivers to roof gutters including irrigation channels. New research investigations include river turbulence, fluvial hydraulics, hydraulic jump flows, undular flows, weir overflow, stepped cascades, dropshafts, energy dissipators and supercritical flows. Applications to hydraulic structures cover high-head spillways, stepped chutes, rubber dams, stilling basins and water quality prediction (e.g. CHANSON 1995, Pergamon; CHANSON 19992004CHANSON 2004). 

Industrial Two-Phase Flows

In high-velocity turbulent flows, air bubbles are entrained at the free surface. This process (self-aeration) is caused by the turbulent velocity fluctuations acting next to the free surfaces. The presence of air within the flow increases the bulk of the flow, modifies the momentum shear layers and enhances the air-water gas transfer. The project is based upon new experimental investigations using large-scale experiments : water jets discharging into the atmosphere, high-velocity open channel flows, hydraulic jumps and plunging water jets. The results enable a better understanding of the fluid mechanics of free-surface air-water flows (CHANSON 1997, Academic Press). Applications include some optimisation of hydraulic structure design, mixing devices in chemical plants, firefighting equipment.

Estuarine Processes

Estuarine processes are complicated phenomena that are in between traditional fluvial and coastal hydraulics. Present studies are focusing on turbulent mixing and turbulence characteristics in estuarine zone. A joint collaboration is underway with Japan to compare systematically the characteristics of shallow water bays and estuaries.
Coastal engineering studies include the hydrodynamics of tidal bores, whirlpools and breaking waves.
Plunging breaking waves have a dominant role in the energy dissipation process. The breaking process is extremely energetic and associated with strong air bubble interactions. The energy radiation of long-period waves is a predominant source of energy in the offshore-onshore direction. The process is extremely important to understand coastal erosion and harbour protection. Two research collaborations are active with Taiwan and Japan. Some results showed that air entrainment at plunging breakers is similar to bubble entrainment by plunging liquid jets. Further 'free' long waves may be generated near the coastline by the water level rise associated with the air entrainment. 

Aeration Technology and Water Quality Modelling

Most assessments of water quality in rivers and ocean are based on dissolved oxygen (DO) levels. Most dissolved oxygen is derived from the free surface aeration which occurs when air bubble clouds are entrained by breaking waves. For example, during storms in the ocean and during spillway releases at a dam. Air-water gas transfer across the bubble interface is predominant as the net surface area of thousands of entrained air bubbles is much greater than the area of the free-surface. New experimental investigations have been conducted to simulate different mechanisms of wave breaking and air bubble entrainment. The results enable a better understanding of the aeration mechanisms. The study is applied to water quality problems downstream of hydraulic structures, the greenhouse effect and ocean-atmosphere gas exchange processes. 

Environmental Management and Sediment Transport

Several studies are conducted in parallel to investigate the historical development of civil engineering and hydraulic structures. Current projects include the early developments of dams, reservoirs and water supply systems in Australia (from the early 1800s to 1950), the history of stepped cascades and chutes (from BC 1300 to today), the introduction of concrete in hydraulic structures during the 19th century. The results of the project bring new lights to present design techniques and trends. For example, for the design of stepped spillways, for the refurbishment of existing weirs and dams, with regards to reservoir siltation. One study is focused on the hydraulics of Roman water supply and aqueducts. An investigation of steep chutes and cascades along aqueducts has highlighted the presence of supercritical flows and hydraulic jumps. Further an unusual type of dissipation structures was used : the Roma dropshaft. Analytical and physical models of dropshaft operation are developed, and the study provides a better understanding of the aqueduct operation. 

Engineering History and Heritage

Several studies are conducted in parallel to investigate the historical development of civil engineering and hydraulic structures. Current projects include the early developments of dams, reservoirs and water supply systems in Australia (from the early 1800s to 1950), the history of stepped cascades and chutes (from BC 1300 to today), the introduction of concrete in hydraulic structures during the 19th century. The results of the project bring new lights to present design techniques and trends. For example, for the design of stepped spillways, for the refurbishment of existing weirs and dams, with regards to reservoir siltation. One study is focused on the hydraulics of Roman water supply and aqueducts. An investigation of steep chutes and cascades along aqueducts has highlighted the presence of supercritical flows and hydraulic jumps. Further an unusual type of dissipation structures was used : the Roma dropshaft. Analytical and physical models of dropshaft operation are developed, and the study provides a better understanding of the aqueduct operation. 

Haigslee - Fernvale road under water on 11 January 2011 (Photograph Hubert CHANSON)