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Christophe Ancey is currently an associate professor at École Polytechnique Fédérale de Lausanne (EPFL) in Switzerland.

Christophe Ancey
Known for	Rhelogy
Scientific career
Fields	Fluid dynamics
Institutions	École polytechnique fédérale de Lausanne
Doctoral advisor	Pierre Evesque; Philippe Coussot
Website	https://people.epfl.ch/christophe.ancey?lang=en

He is the director of Environmental Hydraulics Laboratory (LHE), focusing on the research on rheology of granular flows and sediment transport.

Education and Career

Christophe Ancey receives his PhD degree and engineering degree from Ecole Centrale de Paris and Institut National Polytechnique de Grenoble. He completed the thesis on the rheology of granular flows under the supervision of Pierre Evesque and Philippe Coussot from 1994-1997.

After his dissertation, he became a research fellow in the "protection against erosion" team led by Jean-Pierre Feuvrier at Cemagref in 1998.

In 2003, he joined École Polytechnique Fédérale de Lausanne (EPFL) as an assistant professor. At the same time, he became the director of Environmental Hydraulics Laboratory (LHE) after Walter Graf(1982-2001), Mustapha Altinakar (2002), and Ulrich Lemmin (2003). In 2009, he was promoted to an associated professor in fluid mechanics.

Non-linear relationship between stress $\tau$ and strain γ for plastic material

Christophe Ancey services as an associate editor of Water Resources Research since 2004 and Journal of Geophysical Research: Earth Surface since 2015.

Scientific Research

Christophe Ancey has published more than 80 scientific papers and his h-index on google scholar is 48. Apart from this, 6 books and 12 book chapters are completed by Christophe Ancey. He is active in investigating the problems on granular flows and sediment transport mainly through experiments and theoretical analysis.

Sediment is transported by the river to the coastline of Buenos Aires.

A demonstration of the particle segregation (also known as the Brazil nut effect). A stack of coins will end up on the surface under shaking.

- rheology of granular flow: The behavior of granular flow is quite different from solid mechanism in the view that granular flows deform with an external force, which is also known as plasticity. Physical properties of granular flow such as yield stress, viscosity, the relationship between strain stress $\gamma$ and shear stress $\tau$ are within the investigation scope of Ancey's group.

- sediment transport: Movement of sediments is essential to the erosion or deposition along the riverbed. Intermittent process of sediment transport, the interplay between bedload transport fluctuations and bedforms, and methods for estimating mean bedload transport rates are within the research scope. To understand these problems, microstructural analysis such as particle entrainment, particle suspension, and particle deposition are analyzed.

- particle segregation: The separation of particles with different physical properties under external force is called particle segregation. This phenomenon is quite common in industries (mining, pharmacy, agriculture) and essential to product quality. The purpose of this research project is to investigate the mechanics behind the segregation mainly caused by size differences in granular flows. The continuum model is utilized as a theoretical tool to analyze the dynamics in particle segregation by treating granular flow as a continuum body.

- refractive index matching: This method aims at obtaining the same refractive index for all materials in the experiment domain. In experiments conducted by Christophe Ancey's lab, a uniform refractive index situation is achieved by choosing borosilicate glass as particles, and the mixture of benzyl alcohol and ethanol as the fluids. This allows imaging techniques such as particle image velocimetry (PIV) and laser Doppler velocimetry (LDV) to be applied in experiments to obtain velocity. Further details on the refractive index matching method have been summarized by Ancey's lab.

Teaching and Supervision

Christophe Ancey teaches 4 courses, which are Fluid mechanics (bachelor level), Flood and dam break waves (master level), Hydrological risks and structures (master level), and Similarity and Transport Phenomena in Fluid (doctor level). The courses for bachlor and master are taught in French while the course for doctor is taught in English.

More than 20 doctor students have been supervised by Christophe Ancey.

Business

In 1997, Christophe Ancey set up a consulting company for engineering contracting in torrent protection and avalanches with Claude Charlier. The company is named Toraval and is now the major player in this field in France. In 2003, Vincent Bain joined Toraval before the retirement of Claude Charlier. Toraval provides an integrated numerical tool for the calculation of avalanches and risk management.

Environmental Hydraulics Laboratory (LHE)

An example of refractive-index matching. Transparent particles can be seen in the upper part of the bottle while seems to disappear in the lower part. The blue particle with a different refractive index is put in the bottle as a comparison to the transparent particles.

Environmental Hydraulics Laboratory (LHE) has a long history in hydraulics research. It dates back to the Hydraulic Testing Laboratory established by Alfred Stucky in 1928 in Lausanne, Switzerland, and becomes a hydraulics laboratory at EPFL in 1968. The laboratory is split into two parts in 1982, the one known as Hydraulic Constructions Laboratory (LCH) mainly focuses on water constructions projects, and the other one is Environmental Hydraulics Laboratory (LHE) currently led by Christophe Ancey. LHE marks the turn in research topics from general hydraulics towards environmental hydraulics problems with an emphasis on the geophysical flows in the Alps. Moreover, LHE investigates the incorporation of scientific knowledge into land-use planning policies.