# Fluid Mechanics and Acoustics Laboratory - UMR 5509

LMFA - UMR 5509
Laboratoire de Mécanique des Fluides et d’Acoustique
Lyon
France

## Turbulence & Instabilities

The team activities, rather fundamental, deal with hydrodynamic instabilities, transition to turbulence, turbulent flows and flows at small scale.

T&I news:

### Enseignement innovant: Marc Buffat au journal de 20h de France 2

mercredi 9 septembre 2020

France 3 Rhône-Alpes est venu filmer un cours de mécanique donné par Marc Buffat dans la salle René Michel du bâtiment Oméga de Lyon 1 pour illustrer les méthodes d’enseignement innovantes déployées par (...)

### Wouter Bos raconte ITER à RCF

15 septembre 2020

Wouter Bos a été interviewé par la radio lyonnaise RCF pour parler du projet ITER, réacteur thermonucléaire expérimental international. Ce programme a l’ambition de construire le plus grand tokamak (...)

### Posters doctorants 2A

Nos étudiants doctorants en 2ème année ont réalisé des posters didactiques pendant le confinement. Les consignes et le modèle sont donnés ici. À défaut de pouvoir les accrocher sur les murs du labo pour (...)

Article in Phys. Rev. E (2020)

### Linearly forced isotropic turbulence at low Reynolds numbers

Wouter Bos, Faouzi Laadhari & Wesley Agoua

The forcing strength needed to sustain a flow using linear forcing is investigated. A critical Reynolds number $R_c$ is determined, based on the longest wavelength allowed by the system, the (...)

Article in J. Fluid Mech. (2020)

### Model for classical and ultimate regimes of radiatively driven turbulent convection

Mathieu Creyssels

In a standard Rayleigh–Bénard experiment, a layer of fluid is confined between two horizontal plates and the convection regime is controlled by the temperature difference between the hot lower (...)

Article in Heat Transfer (2020)

### Numerical study of natural convection and acoustic waves using the lattice Boltzmann method

Jaouad Benhamou, Mohammed Jami, Ahmed Mezrhab, Valéry Botton & Daniel Henry

In this paper, the lattice Boltzmann method is used to study the acoustic waves propagation inside a differentially heated square enclosure filled with air. The waves are generated by a point (...)

Article in Computers & Fluids (2020)

### Reducing the background anisotropy by using hexagonal Fourier transform in two-dimensional turbulent flows

J. Chai, Le Fang & Jean-Pierre Bertoglio

The two-dimensional hexagonal Fourier transform is introduced to reduce the background anisotropy in the numerical calculations with periodic conditions. Comparing to traditional Fourier (...)

Article in Phys. Rev. Fluids (2020)

### Transition from non-swirling to swirling axisymmetric turbulence

Zecong Qin, Hugues Faller, Bérengère Dubrulle, Aurore Naso & Wouter Bos

Strictly axisymmetric turbulence, i.e., turbulence governed by the Navier-Stokes equations modified such that the flow is invariant in the azimuthal direction, is a system intermediate between (...)

Article in Phys. Rev. Fluids (2020)

### Single-particle Lagrangian statistics from direct numerical simulations of rotating-stratified turbulence

Dhawal Buaria, Alain Pumir, Fabio Feraco, Raffaele Marino, Annick Pouquet, Duane Rosenberg & Leonardo Primavera

Geophysical fluid flows are predominantly turbulent and often strongly affected by the Earth’s rotation, as well as by stable density stratification. Using direct numerical simulations of forced (...)

Article in J. Fluid Mech. (2020)

### Numerical study of extreme mechanical force exerted by a turbulent flow on a bluff body by direct and rare-event sampling techniques

Thibault Lestang, Freddy Bouchet & Emmanuel Lévêque

This study investigates, by means of numerical simulations, extreme mechanical force exerted by a turbulent flow impinging on a bluff body, and examines the relevance of two distinct rare-event (...)

Article in Atmosphere (2020)

### Partitioning Waves and Eddies in Stably Stratified Turbulence

Henri Lam, Alexandre Delache & Fabien Godeferd

We consider the separation of motion related to internal gravity waves and eddy dynamics in stably stratified flows obtained by direct numerical simulations. The waves’ dispersion relation links (...)

This study investigates the effects of a Bethe–Zel’dovich–Thompson (BZT) dense gas (FC-70) on the development of a turbulent compressible mixing layer at a convective Mach number $M_c=1.1$. (...)