Lagrangian study of an inhomogeneous turbulence

PhD project

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).
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).

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.

CONTACTS

  • PI: Nicolas Mordant
  • Co-PI: Mickaël Bourgoin
  • PhD: Nick Stelzenmuller

PARTNERS

  • LEGI
  • Ecole Centrale Lyon

FUNDING

Tec21

 

 

 


Outcomes

 

 

PUBLICATIONS

  • Polanco, J. I., Vinkovic, I., Stelzenmuller, N., Mordant, N., & Bourgoin, M. (2018). Relative dispersion of particles paris in turbulent flows. Int. J. Heat Fluid Flow, 64, 231-245. https://doi.org/10.1016/j.ijheatfluidflow.2018.04.007
  • Stelzenmuller, N., Polanco, J. I., Vignal, L., Vinkovic, I., & Mordant, N. (2017). Lagrangian acceleration statistics in a turbulent channel flow. Phys. Rev. Fluids, 2, 054602. https://doi.org/10.1103/PhysRevFluids.2.054602
  • Bourgoin, M., Baudet, C., Kharche, S., Mordant, N., Vandenberghe, T., Sumbekova, S., ... Peinke, J. (2017) Investigation of the small-scale statistics of turbulence in the Modane S1MA wind tunnel. CEAS Aeronautical Journal, 9, 269-281.

CONFERENCES

  • Lagrangian statistics in a turbulent channel, ETC16, 2017, Stockholm (Sweden)

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

  • Lagrangian study of inhomogeneous turbulence: Experimental results, EFMC 11 2016, Seville (Spain)

  • Une étude Lagrangienne de la turbulence inhomogène, GdR Turbulence, 2016, Paris (France)

  • An experimental Lagrangian study of inhomgeneous turbulence, APS DFD, 2015, Boston (USA)

  • Etude lagrangienne de la dispersion dans un canal plan turbulent, CFM 2015 Lyon (France)

  • Mesures lagrangiennes dans un écoulement de canal plan turbulent, GdR Turbulence, 2015, Grenoble (France)