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PhD Project: Lagrangian study of an inhomogeneous turbulence


Starting: December 2013

 

The transport of a passive scalar such as a pollutant, by a high Reynolds number turbulent flow is intimately related to the statistical properties of the fluid particles trajectories. The recent developments of high speed cameras enabling to track the motion of particles in high velocity flows, gave access to the Lagrangian properties of turbulence (i.e. turbulence seen from the particle’s point of view). In the last 15 years, studies focusing on homogeneous systems have renewed the experimental approach of turbulence. But most situations of practical interest are inhomogeneous. It is the case of the atmospheric boundary layer (the few hundred meters above the Earth’s surface), where the flow is extremely turbulent and shows a vertical gradient of velocity. 

In this project, a high aspect ratio channel flow will be used as a benchmark case of turbulent boundary layers. This flow exhibits symmetry properties that will make the experimental study simpler. Eulerian measurements will be carried out to fully characterize the flow, and the study will then focus on Lagrangian properties, starting with the acceleration. The dispersion of fluid particles at longer timescales will then be addressed, and the experimental data will be compared to numerical simulations performed by I. Vinkovic and M. Gorokhovski in Ecole Centrale Lyon.

 

The aim is to better understand the influence of the velocity gradient on the fluid particles trajectories, in order to accurately model the transport properties in this region of the atmosphere.


Polystyrene particles (10 µm) doped with Rhodamine in a turbulent flow. The flow is illuminated by YAG laser sheet and the fluorescent particles are isolated from the illuminated background by a red filter (exposure time: 1/250 sec). 

PI: Nicolas Mordant; Co-PI: Mickaël Bourgoin; PhD Student: Nick Stelzenmuller (see his CV) 


Project update

Articles

 

Juan Ignacio Polanco, Ivana Vinkovic, Nickolas Stelzenmuller, Nicolas Mordant, Mickael Bourgoin: Relative dispersion of particle pairs in turbulent channel flow. International Journal of Heat and Fluid Flow, (In press)

 

Nickolas Stelzenmuller, Juan Ignacio Polanco, Laure Vignal, Ivana Vinkovic, and Nicolas Mordant: Lagrangian acceleration statistics in a turbulent channel flow. Phys. Rev. Fluids 2, 054602 – Published 2 May 2017

 

Bourgoin, M, Baudet, C, Kharche, S, Mordant, N, Vandenberghe, T, Sumbekova, S, Stelzenmuller, N, Aliseda, A, Gibert, M, Roche, P-E et al.: Investigation of the small-scale statistics of turbulence in the Modane S1MA wind tunnel. CEAS Aeronautical Journal, 2017

 

Conferences

 

Lagrangian statistics in a turbulent channel, ETC16, 2017, Stockholm

 

Lagrangian statistics in turbulent channel flow: implications for Lagrangian stochastic models, APS DFD, 2016, Portland

 

Lagrangian study of inhomogeneous turbulence: Experimental results, EFMC 11 2016, Séville

 

Une étude Lagrangienne de la turbulence inhomogène, GdR Turbulence, 2016, Paris

 

An experimental Lagrangian study of inhomgeneous turbulence, APS DFD, 2015, Boston

 

Etude lagrangienne de la dispersion dans un canal plan turbulent, CFM 2015 Lyon

 

Mesures lagrangiennes dans un écoulement de canal plan turbulent, GdR Turbulence, 2015, Grenoble

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