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Christophe Ancey

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Publications associées (96)

Decoupling the role of inertia, friction and cohesion in dense granular avalanche pressure build‐up on obstacles

Christophe Ancey, Johan Alexandre Philippe Gaume, Michael Lukas Kyburz

Understanding the physical processes involved in snow avalanche‐obstacle interaction is essential to be able to estimate the pressure exerted on structures. Although avalanche impact pressure has been measured in field experiments for decades, the underlyi ...

2020

Estimating Mean Bedload Transport Rates and Their Uncertainty

Christophe Ancey, Ivan Pascal

Measuring bedload transport rates usually involves measuring the flux of sediment or collecting sediment during a certain interval of time Δt. Because bedload transport rates exhibit significant non‐Gaussian fluctuations, their time‐averaged rates depend a ...

2020

Using a Data Driven Approach to Predict Waves Generated by Gravity Driven Mass Flows

Christophe Ancey, Zhenzhu Meng, Yating Hu

When colossal gravity-driven mass flows enter a body of water, they may generate waves which can have destructive consequences on coastal areas. A number of empirical equations in the form of power functions of several dimensionless groups have been develo ...

2020

Modeling turbulent stream flows over rough permeable beds

Christophe Ancey, Gauthier Paul Daniel Marie Rousseau, Ivan Pascal

In steep streams, turbulent flows run over coarse sediments that are similar in size to flow depth. Under these conditions, a significant part of the flow may seep through the permeable bed. Based on experimental data, this paper presents a model able to r ...

CRC Press2020

Antidunes on steep slopes: variability of wave geometry and migration celerity

Christophe Ancey, Ivan Pascal

As a result of interactions between streamflow andsediment, riverbeds are seldom smooth, but depending onhydraulic and sediment transport conditions, they exhibitbedforms, which grow and migrate over time (upstreamor downstream). Morphology migration may e ...

Heide Friedrich and Karin Bryan2019

Hydraulic Reconstruction of the 1818 Gietro Glacial Lake Outburst Flood

Eric Bardou, Christophe Ancey, Martin Funk, Tomás Alfredo Trewhela Palacios

In the spring of 1818, ice avalanches from the Gietro Glacier created an ice dam, which in turn formed a glacial lake in the Drance Valley (Canton of Valais, Switzerland). Today, its maximum volume is estimated to have been 25x10(6) m(3). Cantonal authorit ...

2019

The effects of slide cohesion on impulse-wave formation

Christophe Ancey, Zhenzhu Meng

Experimental studies of impulse-wave formation have mostly used rigid blocks or granular materials to mimic landslides at the laboratory scale. These studies have deduced that material deformability plays a key part in wave formation: the more rigid the sl ...

2019

Are Bedload Transport Pulses in Gravel Bed Rivers Created by Bar Migration or SedimentWaves?

Christophe Ancey, Blaise Etienne Marceau Dhont

Bedload transport exhibits considerable spatial and temporal variability, as reflected by large fluctuations of transport rates. Among the various mechanisms proposed for explaining this variability, bedform migration is often cited as the main cause. We t ...

2018

Avalanche pressures at the Vallée de la Sionne test site: interaction of avalanches and narrow strictures studied with DEM

Christophe Ancey, Johan Alexandre Philippe Gaume

2018

Breaking size-segregation waves and mobility feedback in dense granular avalanches

Christophe Ancey, Kasper van der Vaart

Through experiments and discrete particle method (DPM) simulations we present evidence for the existence of a recirculating structure, that exists near the front of dense granular avalanches, and is known as a breaking size-segregation (BSS) wave. This is ...

2018

Stochastic bedload transport in mountain streams

Christophe Ancey

Describing bedload transport as a stochastic process is an idea that emerged in the 1930s with the pioneering work of Einstein. For a long time, the stochastic approach attracted marginal attention, but the situation has radically changed over the last dec ...

EDP Sciences2018

Segregation of large particles in dense granular flows suggests a granular Saffman effect

Christophe Ancey, Kasper van der Vaart

We report on the scaling between the lift force and the velocity lag experienced by a single particle of different size in a monodisperse dense granular chute flow. The similarity of this scaling to the Saffman lift force in (micro-) fluids, suggests an in ...

2018

How bar generate sediment transport pulses in gravel-bed channels

Christophe Ancey, Blaise Etienne Marceau Dhont, Ivan Pascal

We ran flume experiments with constant water dis- charge and sediment feed rate at the inlet. Experi- ments were conducted over long times (typically 600 h). The bars migrated downstream intermittently, producing the most important pulses. When the bar pos ...

IAHR2018

Monitoring geomorphological changes due to debris flows in mountain rivers using UAV: exploiting similarities between Alpine and Andean regions

Christophe Ancey, Tomás Alfredo Trewhela Palacios

Definition of proper methodologies for unmanned aerial vehicle (UAV) to monitor debris flows will be done in two workshops: one in each participant institution. The objective is to do field demonstrations and measurements to exploit similarities between Al ...

2018

Bar dynamics and sediment transport pulses in gravel-bed channels

Christophe Ancey, Blaise Etienne Marceau Dhont

Mountain rivers exhibit sediment transport rate fluctuations that often cover more than two orders of magnitude. Bedform migration is often cited as the key process that causes giant fluctuations in the sediment transport rate. To quantify the effect of be ...

EDP Sciences2018

The dam-break problem for eroding viscoplastic fluids

Christophe Ancey, Belinda Margaret Bates

Natural gravity-driven flows can increase in volume by eroding the bed on which they descend. This process is called basal entrainment and is thought to play a key role in the bulk dynamics of geophysical flows. Although its study is difficult using field ...

Elsevier2017

Stokes' third problem for Herschel-Bulkley fluids

Christophe Ancey, Belinda Margaret Bates

Herschel-Bulkley materials can be set in motion when a sufficiently high shear stress or body force is applied to them. We investigate the behaviour of a layer of Herschel-Bulkley fluid when it is suddenly tilted and subject to gravitational forces. The ma ...

Elsevier2017

Continuous Monitoring of Bed-Load Transport in a Laboratory Flume Using an Impact Sensor

Christophe Ancey, Blaise Etienne Marceau Dhont, Gauthier Paul Daniel Marie Rousseau

Bed-load transport rate in gravel-bed rivers shows large non-Gaussian fluctuations, even under steady flow conditions. The development of high-resolution measurement techniques during the last two decades creates research opportunities to study the intermi ...

American Society of Civil Engineers2017

Basal entrainment by Newtonian gravity-driven flows

Nicolas Andreini, Christophe Ancey, Belinda Margaret Bates

Gravity-driven flows can erode the bed along which they descend and increase their mass by a factor of 10 or more. This process is called "basal entrainment." Although documented by field observations and laboratory experiments, it remains poorly understoo ...

Amer Inst Physics2016

Impulse waves generated by snow avalanches: Momentum and energy transfer to a water body

Christophe Ancey

When a snow avalanche enters a body of water, it creates an impulse wave whose effects may be catastrophic. Assessing the risk posed by such events requires estimates of the wave’s features. Empirical equations have been developed for this purpose in the c ...

Wiley-Blackwell2016

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