Séminaire

Vendredi 19 Décembre 2025 à 11h00.

Particle dispersion in turbulence: a Lagrangian perspective to deal with inhomogeneity

Thomas BASSET
(Institut Lumière Matière)

Salle de séminaires Lippmann

Invité(e) par
Anne-Laure BIANCE

présentera en 1 heure :

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The classical framework used to describe turbulence, known as Kolmogorov phenomenology, is limited to homogeneous isotropic stationary turbulence. For particle dispersion, this becomes even more complex, as Lagrangian dynamics in an inhomogeneous but stationary flow will not be stationary. In this seminar, based on two Lagrangian experiments and the associated trajectory databases, I will present two cases of inhomogeneity in turbulence, specifically using the concept of turbulent diffusion.

First, a Lagrangian experimental study of a turbulent jet, a canonical inhomogeneous flow, was carried out [1]. The influence of inhomogeneous nozzle seeding is described quantitatively. This approach, which reveals the original phenomenon of effective compressibility, allows a new understanding of entrainment and turbulent diffusion in a jet.

Second, we propose a model for the secular problem of pair dispersion (inhomogeneity through scales) within the framework of ballistic cascade phenomenology [2]. A new stochastic formulation is developed and confronted to experimental data in homogeneous isotropic turbulence. This model is partially validated, showing in particular an unexpected non-Kolmogorovian scaling.

[1] Basset et al. 2022, J. Fluid Mech. 947, A29. doi:10.1017/jfm.2022.638
[2] Bourgoin 2015, J. Fluid Mech. 772, 678-707. doi:10.1017/jfm.2015.206

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