24 octobre 2019

Seminar Francesco Romano

Francesco Romano is assistante professor at ENSAM Lille and is part of LMFL since September 1st, 2019.
Particle coherent structures in incompressible fluid flows

The motion of small particles in incompressible steady flows can be strongly characterized by the creation of particle attractors. Several dissipative mechanisms may lead to the accumulation of particles, such as inertial forces due to the particle-fluid density mismatch or to finite-size effects in the bulk. Other dissipative effects which may lead to attractors are due to gravity and Basset history forces. The particle accumulation mechanism of interest in this talk relies on the interaction of the particles with undeformable boundaries, very frequent in boundary-driven flows. For dilute suspensions, these accumulation phenomena are successfully modeled as single-particle attractions and are strongly correlated to the topology of the fluid flow without particles. When the accumulations are in form of periodic or quasi-periodic patterns, they are termed finite-size Lagrangian coherent structures, since they are the result of the Lagrangian topology of the fluid flow and of the finite-size effect of the particle near the boundary. Boundary-driven flows will be considered to demonstrate the relative importance of the several dissipation mechanisms which affect the particle motion. A comparison between numerical simulations and experiments will be presented to further strengthen the theoretical understanding of finite-size Lagrangian coherent structures.

Abstract

24 octobre 2019, 09h0010h00
LMFL, M6 Building, Cité Scientifique, Villeneuve d'Ascq

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17 octobre 2019

Seminar Yi Zhou

The non-Kolmogorov -5/3 spectra and the related scale-by-scale energy transfer in turbulent flows behind two side-by-side square cylinders

Yi Zhou is Associate Professor at School of Energy and Power Engineering, Nanjing University of Science and Technology, China