Effective transport coefficients in Rayleigh-Bénard convection and spatio-temporal statistics in the turbulent jet.
| Quand ? |
Le 29/01/2026, de 11:00 à 12:00 |
|---|---|
| Où ? | Salle des thèses |
| Participants |
Martin Caelen |
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We present two different experiments:
1) We study Rayleigh-Bénard convection in the presence of an externally forced (Roberts-like) cellular flow. This forcing is obtained by placing the convective cell, filled with liquid metal (Galinstan), against an array of permanent magnets, and by injecting a controlled lateral electric current through the liquid metal.
Studying the heat transport properties of the flow below and close to the Rayleigh-Bénard onset of instability, we propose an experimental measurement of the effective transport coefficients (thermal diffusivity and viscosity) as functions of the Péclet number of the forced cellular flow.
2) We present results on the spatio-temporal statistics of velocity fluctuations in a turbulent round jet. The turbulent flow of a round jet is known to be self-similar. For instance, its mean kinetic energy dissipation rate follows a power law in the distance along the jet. We show that the same applies for its 2-points statistics (with an emphasis on its cross-correlation and coherence functions). Departure from Taylor’s frozen-flow hypothesis, with the so-called elliptic approximation, is also discussed.