Publications associées à A multi-site, year-round turbulence microstructure atlas for the deep perialpine Lake Garda

Numerical simulation of the fate, transport and public health risks of enteric viruses in Lake Geneva

Lakes are a fundamental feature of nature with brilliance, profoundness and complexity. Various of physical, chemical and biological changes take place three dimensionally in deep lakes, regulated by complicated boundary conditions. To understand and predi ...

EPFL2023

Spatial Variability of Turbulent Mixing From an Underwater Glider in a Large, Deep, Stratified Lake

Alfred Johny Wüest, Sébastien Lavanchy, Damien Bouffard, Bieito Fernandez Castro, Oscar Rodrigo Sepúlveda Steiner, Alexander Lebaron Forrest

Recent efforts using microstructure turbulence measurements have contributed to our understanding of the overall energy budget in lakes and linkages to vertical fluxes. A paucity of lake-wide turbulence measurements hinders our ability to assess how repres ...

AMER GEOPHYSICAL UNION2023

Density currents driven by differential cooling in lakes: occurrence, dynamics and implications for littoral-pelagic exchange

Tomy Doda

Cross-shore flows exchange water laterally in lakes, with ecological implications for the ecosystem. One example is the convective circulation induced by differential cooling, also known as the thermal siphon. This lateral flow forms when the sloping sides ...

EPFL2022

Growth, timing, & trajectory of vortices behind a rotating plate

Diego Francescangeli

The presence of aerodynamic vortices is widespread in nature. They can be found at small scales near the wing tip of flying insects or at bigger scale in the form of hurricanes, cyclones or even galaxies. They are identified as coherent regions of high vor ...

EPFL2022

Moored observations of turbulent mixing events in deep Lake Garda, Italy

Marco Toffolon, Sebastiano Piccolroaz

Deep water circulation and mixing processes are responsible for the transport of matter, nutrients and pollutants in deep lakes. Nevertheless, detailed continuous observations are rarely available. To overcome some of these deficiencies and with the aim of ...

2021

Inhibited vertical mixing and seasonal persistence of a thin cyanobacterial layer in a stratified lake

Alfred Johny Wüest, Damien Bouffard, Bieito Fernandez Castro, Oscar Rodrigo Sepúlveda Steiner

Harmful blooms of the filamentous cyanobacteria Planktothrix rubescens have become common in many lakes as they have recovered from eutrophication over the last decades. These cyanobacteria, capable of regulating their vertical position, often flourish at ...

2021

Continuously-fed density currents over impermeable and porous substrates

Sara Venuleo

Gravity currents are buoyancy-driven flows having a significant impact on the environment and human life. They can be observed in a vast range of natural and anthropogenic scenarios, such as seawater and freshwater, the atmosphere, or industrial processes. ...

EPFL2020

Convection in Lakes

Alfred Johny Wüest, Damien Bouffard

Lakes and other confined water bodies are not exposed to tides, and their wind forcing is usually much weaker compared to ocean basins and estuaries. Hence, convective processes are often the dominant drivers for shaping mixing and stratification structure ...

2019

Stability of spatial patterns in water chemistry across temperate ecoregions

Camille Roland Marie Minaudo

Human activity has polluted freshwater ecosystems across the planet, harming biodiversity, human health, and the economy. Improving water quality depends on identifying pollutant sources in river networks, but pollutant concentrations fluctuate in time. Co ...

2019

Large-scale and meso-scale surface heat flux patterns of Lake Geneva

Abolfazl Irani Rahaghi

Diverse studies have confirmed the adverse impact of global climate change in lakes. In order to establish effective water quality management policies, it is essential to understand how the heat exchange between the atmosphere and the lake evolves under th ...

EPFL2018

Global and local anthropogenic effects on hydrodynamics of lakes : applications to Lake Biel drinking water management

Carl Love Mikael Råman Vinnå

In many countries water quality is a major concern for drinking water management authorities. Freshwater is a limited resource and the demand for good-quality water from natural aquatic systems is therefore high. Additional stress arises from anthropogenic ...

EPFL2018

Direct numberical simulation of turbulent slope flows up to Grash of number Gr=2.1 x 10(11)

Jiannong Fang, Marc Parlange, Marco Giovanni Giometto, Gabriel George Katul

Stably stratified turbulent flows over an unbounded, smooth, planar sloping surface at high Grashof numbers are examined using direct numerical simulations ( DNS). Four sloping angles ( alpha = 15 degrees; 30 degrees; 60 degrees and 90 degrees) and three G ...

Cambridge University Press2017

Katabatic Flow: A Closed-Form Solution with Spatially-Varying Eddy Diffusivities

Peter Monkewitz, Jiannong Fang, Marc Parlange, Marco Giovanni Giometto

The Nieuwstadt closed-form solution for the stationary Ekman layer is generalized for katabatic flows within the conceptual framework of the Prandtl model. The proposed solution is valid for spatially-varying eddy viscosity and diffusivity (O'Brien type) a ...

Springer Verlag2017

Identification of a Predator-Prey System from Simulation Data of a Convection Model

Jan Sickmann Hesthaven

The use of low-dimensional dynamical systems as reduced models for plasma dynamics is useful as solving an initial value problem requires much less computational resources than fluid simulations. We utilize a data-driven modeling approach to identify a red ...

American Institute of Physics2017

Turbulent planar wakes under pressure gradient conditions

Fernando Porté Agel, Sina Shamsoddin

Accurate prediction of the spatial evolution of turbulent wake flows under pressure gradient conditions is required in some engineering applications such as the design of high-lift devices and wind farms over topography. In this paper, we aim to develop an ...

Cambridge University Press2017

Wake flow in a wind farm during a diurnal cycle

Fernando Porté Agel, Mahdi Abkar, Ahmad Sharifi

The atmospheric boundary layer (ABL) undergoes substantial changes in its structure and dynamics in the course of a day due to the transient nature of forcing factors such as the surface fluxes of heat and momentum. The non-stationary nature of the mean wi ...

Taylor & Francis2016

Influence of the Coriolis force on the structure and evolution of wind turbine wakes

Fernando Porté Agel, Mahdi Abkar

In this study, large-eddy simulation combined with a turbine model is used to investigate the effect of vertical wind veer associated with the Coriolis force on the structure and evolution of wind turbine wakes. In order to isolate the Coriolis effect on t ...

Amer Physical Soc2016

Effects of climate change on deep-water oxygen and winter mixing in a deep lake (Lake Geneva)

Alfred Johny Wüest, Damien Bouffard, Robert Vincent Schwefel

Oxygen is the most important dissolved gas for lake ecosystems. Because low oxygen concentrations are an ongoing problem in many parts of the oceans and numerous lakes, oxygen depletion processes have been intensively studied over the last decades and were ...

2016

Theoretical and numerical studies of atmospheric boundary-layer flows over complex terrain

Marco Giovanni Giometto

Atmospheric boundary-layer (ABL) flows over complex terrain have been the focus of active research, given their impact on weather and climate variability. Surface complexity is understood in a broad sense and includes variation in roughness properties, inc ...

EPFL2016

Oxygen depletion in stratified lakes - why shallow and deep lakes react differently

Alfred Johny Wüest, Robert Vincent Schwefel

Oxygen is the most important element in natural waters for any higher aquatic life, such as fish. As with humans, almost all members of aquatic ecosystems need oxygen to breathe. Building on this, treatment of drinking water is easier for oxic than for ano ...

2016