Publications related to Wake turbulence

Validation of short-pulse reflectometry turbulence measurements with a synthetic diagnostic

Stefano Coda, Stephan Brunner, Oleg Krutkin, Umesh Kumar, Mackenzie Peter-Fulford Van Rossem, Samuele Mazzi

Experimental measurements of the turbulence amplitude utilizing a short pulse reflectometry method are presented. Two discharges with shaped plasma possessing opposite signs of triangularity are considered and a higher turbulence amplitude is found in the ...

IOP Publishing Ltd2024

Enhancing Wind Farm Performance through Axial Induction and Tilt Control: Insights from Wind Tunnel Experiments

Fernando Porté Agel, Guillem Armengol Barcos

Static axial induction control and tilt control are two strategies that have the potential to increase power production in wind farms, mitigating wake effects and increasing the available power for downstream turbines. In this study, wind tunnel experiment ...

MDPI2024

Numerical study on the scale effect of tip vortex cavitation induced by incoming velocities and scale ratios

Mohamed Farhat, Huaiyu Cheng, Mohan Xu

Large eddy simulations of tip vortex cavitation (TVC) around an elliptical hydrofoil is performed to study its scale effect. A satisfying agreement is obtained between the numerical and experimental data. It indicates that the scale effect of TVC is remark ...

PERGAMON-ELSEVIER SCIENCE LTD2023

Validation of GBS plasma turbulence simulation of the TJ-K stellarator

Paolo Ricci, Joaquim Loizu Cisquella

We present a validation of a three-dimensional, two-fluid simulation of plasma turbulence in the TJ-K stellarator, a low temperature plasma experiment ideally suited for turbulence measurements. The simulation is carried out by the GBS code, recently adapt ...

IOP Publishing Ltd2023

The hunt for the Karman 'constant' revisited

Peter Monkewitz

The log law of the wall, joining the inner, near-wall mean velocity profile (MVP) in wall-bounded turbulent flows to the outer region, has been a permanent fixture of turbulence research for over hundred years, but there is still no general agreement on th ...

Cambridge University Press2023

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

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

The effects of kinematics, flexibility, and planform on the vortex formation and aerodynamic performance of flapping wing flight

Alexander Gehrke

In this thesis, the aerodynamic challenges in flapping wing flight are addressed. In particular, the effects of different wing kinematics, flexibilities, and planforms on the the leading edge vortex development and aerodynamic performance are investigated. ...

EPFL2023

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

Effects of leading-edge separation on the vortex-induced vibration of an elongated bluff body

Guiyue Duan, Hongyu Li

Wind-tunnel experiments were conducted to investigate the effects of leading-edge separation on the vortex-induced vibration (VIV) of an elastically-supported elongated bluff body. Solid wind barriers of various heights were fixed in the leading edge to ad ...

ELSEVIER2021

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

Sebastiano Piccolroaz, Bieito Fernandez Castro, Marco Toffolon

A multi-site, year-round dataset comprising a total of 606 high-resolution turbulence microstructure profiles of shear and temperature gradient in the upper 100 m depth is made available for Lake Garda (Italy). Concurrent meteorological data were measured ...

2021

Turbulence and flows in the plasma boundary of snowflake magnetic configurations

Paolo Ricci, Louis Nicolas Stenger, Maurizio Giacomin

Results of 3D, flux-driven, global, two-fluid turbulence simulations are presented for the first time in snowflake (SF) configurations, including the ideal SF, SF plus and SF minus configurations. The analysis is focused on the distribution of the heat flu ...

IOP Publishing Ltd2020

Generation of chiral asymmetry via helical magnetic fields

Ruth Durrer, Jennifer Waltraud Schober

It is well known that helical magnetic fields undergo a so-called inverse cascade by which their correlation length grows due to the conservation of magnetic helicity in classical ideal magnetohydro-dynamics (MHD). At high energies above approximately 10 M ...

American Physical Society2020

Flow dynamics of a dandelion pappus: A linear stability approach

François Gallaire, Pier Giuseppe Ledda, Francesco Viola, Lorenzo Siconolfi

The study and control of flow instabilities is a key problem in aerodynamics. Aircrafts are designed not only to generate the lift force needed to balance their weight but, more importantly, to be stable and reasonably steady when in cruise conditions. Sim ...

2019

Suppressing tip vortex cavitation by winglets

Mohamed Farhat, Ali Amini, Martino Reclari

Despite the numerous remedies prescribed so far, tip vortex cavitation (TVC) remains a major issue in design and operation of diverse applications. In this paper, we experimentally investigate the effectiveness of winglets in suppressing TVC. An elliptical ...

SPRINGER2019

Wind Turbine Wake Characterization with Nacelle-Mounted Wind Lidars for Analytical Wake Model Validation

Fernando Porté Agel, Corey Dean Markfort, Fernando Carbajo Fuertes

This study presents the setup, methodology and results from a measurement campaign dedicated to the characterization of full-scale wind turbine wakes under different inflow conditions. The measurements have been obtained from two pulsed scanning Doppler li ...

2018

Experimental demonstration of the water-holding property of three-dimensional vortices

When injecting dye into a vertical vortex generated by a commercial magnetic stirrer, one finds that dye remains captured around the vortex core over minutes, while it gets mixed with the water outside this region rather rapidly. Thus, considering its hori ...

IOP Publishing - EPL Association2018

Unsteady fluid dynamics around a hovering flat plate wing

Swathi Badala Krishna

Insect flight is characterised by complex time-dependent flows in response to the unsteady wing movements. Biological fliers exploit the unsteady flow fields to modulate aerodynamic forces, thereby displaying unmatched flight performance, especially in hov ...

EPFL2017

Wind tunnel study of the wind turbine interaction with a boundary-layer flow: Upwind region, turbine performance, and wake region

Fernando Porté Agel, Majid Bastankhah

Comprehensive wind tunnel experiments were carried out to study the interaction of a turbulent boundary layer with a wind turbine operating under different tip-speed ratios and yaw angles. Force and power measurements were performed to characterize the var ...

Amer Inst 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

Outer midplane scrape-off layer profiles and turbulence in simulations of Alcator C-Mod inner-wall limited discharges

Federico David Halpern

A region of steep plasma gradients, the so-called "narrow-feature," has been found in the near scrape-off layer (SOL) of inner-wall limited (IWL) discharges. Dedicated IWL discharges were carried out in Alcator C-Mod [Marmar et al., Nucl. Fusion 55, 104020 ...

Amer Inst Physics2017