Publications de Marc Calaf Bracons

Mean kinetic energy distribution in finite-size wind farms: A function of turbines' arrangement

Marc Calaf Bracons, Roberto Torres Sánchez, Varun Sharma

In this work the redistribution and recovery of mean kinetic energy in a realistic, finite size wind farm is studied for neutral atmospheric boundary layer conditions. Five different wind farm configurations, with different wind turbine arrangements, are c ...

Pergamon-Elsevier Science Ltd2020

Evolution of flow characteristics through finite-sized wind farms and influence of turbine arrangement

Marc Parlange, Marc Calaf Bracons, Fabien Margairaz, Varun Sharma

Pergamon-Elsevier Science Ltd2018

Pathways for mitigating thermal losses in solar photovoltaics

Marc Calaf Bracons, Olivier Denis Dupré

To improve the performance of solar photovoltaic devices one should mitigate three types of losses: optical, electrical and thermal. However, further reducing the optical and electrical losses in modern photovoltaic devices is becoming increasingly costly. ...

Nature Research2018

Wind farm density and harvested power in very large wind farms: A low-order model

Marc Calaf Bracons, Varun Sharma

In this work we create new understanding of wind turbine wakes recovery process as a function of wind farm density using large-eddy simulations of an atmospheric boundary layer diurnal cycle. Simulations are forced with a constant geostrophic wind and a ti ...

Amer Physical Soc2017

Investigation of the incoming wind vector for improved wind turbine yaw-adjustment under different atmospheric and wind farm conditions

Marc Calaf Bracons, Varun Sharma

Regardless of the evolution of wind energy harvesting, the way in which turbines obtain in-situ meteorological information remains the same - i.e. using traditional wind vanes and cup anemometers installed at the turbine's nacelle, right behind the blades. ...

Pergamon-Elsevier Science Ltd2017

Perturbations to the Spatial and Temporal Characteristics of the Diurnally-Varying Atmospheric Boundary Layer Due to an Extensive Wind Farm

Marc Parlange, Marc Calaf Bracons, Varun Sharma

The effect of extensive terrestrial wind farms on the spatio-temporal structure of the diurnally-evolving atmospheric boundary layer is explored. High-resolution large-eddy simulations of a realistic diurnal cycle with an embedded wind farm are performed. ...

Springer Verlag2017

Controls on the diurnal streamflow cycles in two subbasins of an alpine headwater catchment

Marc Parlange, Marc Calaf Bracons, Raphaël Mutzner, Holly Jayne Oldroyd, Steven Vincent Weijs

In high-altitude alpine catchments, diurnal streamflow cycles are typically dominated by snowmelt or ice melt. Evapotranspiration-induced diurnal streamflow cycles are less observed in these catchments but might happen simultaneously. During a field campai ...

American Geophysical Union2015

Time-adaptive wind turbine model for an LES framework

Marc Parlange, Marc Calaf Bracons, Michael Lehning, Varun Sharma

Most large-eddy simulation studies related to wind energy have been carried out either by using a fixed pressure gradient to ensure that mean wind direction is perpendicular to the wind turbine rotor disk or by forcing the flow with a geostrophic wind and ...

Wiley-Blackwell2015

Large Wind Farms and the Scalar Flux over an Heterogeneously Rough Land Surface

Marc Parlange, Marc Calaf Bracons, Chad Higgins

The influence of surface heterogeneities extends vertically within the atmospheric surface layer to the so-called blending height, causing changes in the fluxes of momentum and scalars. Inside this region the turbulence structure cannot be treated as horiz ...

Springer Verlag2014

Coherent structures and the k(-1) spectral behaviour

Valentin Simeonov, Marc Parlange, Marc Calaf Bracons, Holly Jayne Oldroyd

l Here we present unique evidence of a k(-1) scaling behaviour in the atmospheric boundary layer and its connection to large scale coherent structures within the boundary layer. Wind lidar measurements were conducted above a lake under cold atmospheric con ...

Amer Inst Physics2013

A New Wall Shear Stress Model for Atmospheric Boundary Layer Simulations

Marc Parlange, Marc Calaf Bracons

A new wall shear stress model to be used as a wall boundary condition for large-eddy simulations of the atmospheric boundary layer is proposed. The new model computes the wall shear stress and the vertical derivatives of the streamwise velocity component b ...

American Meteorological Society2013

Carbon monoxide as a tracer of gas transport in snow and other natural porous media

Marc Parlange, Marc Calaf Bracons, Wolf Hendrik Huwald, Scott W. Tyler, Nicolaas Cornelis van de Giesen

The movement of air in natural porous media is complex and challenging to measure. Yet gas transport has important implications, for instance, for the evolution of the seasonal snow cover and for water vapor transport in soil. A novel in situ multi-sensor ...

American Geophysical Union2012

Large Eddy Simulation study of a fully developed thermal wind-turbine array boundary layer

Marc Parlange, Marc Calaf Bracons, Charles Vivant Ignacio Meneveau

When wind turbines are arranged in large wind farms, their efficiency decreases significantly due to wake effects and to complex turbulence interactions with the atmospheric boundary layer (ABL) [1]. For large wind farms whose length exceeds the ABL height ...

2011

Study of a Fully Developed Wind Turbine Array Boundary Layer

Marc Calaf Bracons

Wind harvesting is fast becoming an important alternative source of energy. As wind farms become larger, they begin to attain scales at which two-way interactions with the atmospheric boundary layer (ABL) must be taken into account. Several studies (Baidya ...

EPFL2011

Large eddy simulation study of fully developed wind-turbine array boundary layers

Marc Calaf Bracons, Charles Vivant Ignacio Meneveau

It is well known that when wind turbines are deployed in large arrays, their efficiency decreases due to complex interactions among themselves and with the atmospheric boundary layer (ABL). For wind farms whose length exceeds the height of the ABL by over ...

2010