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Lagrangian subgrid modelling for the relative separation of tracers in turbulence

Event Type: 
Date and Time: 
Friday, October 2, 2015 - 16:00
Location: 
CTR Conference Room 103
Event Sponsor: 
Parviz Moin, Director of Center for Turbulence Research
Speaker(s): 
Dr. Federico Toschi, Team Leader PIV, German Aerospace Center

Turbulence has an important influence on the transport of small particulate matter like dust in the atmosphere, fuel droplets in combustion chambers and small biological organisms in marine environments.

The relative separation of small tracer particles is strongly influenced by the multi-­‐scale space and time correlations of the turbulent velocity field. While in applications it is often necessary to model the smallest turbulent scales, this may have an important impact on particles’ dynamics and in particular on their relative dispersion.

We present recent results on the dispersion of particle pairs studied by means of fully resolved high-­‐ resolution and high-­‐statistics direct numerical simulations [1,2]. We further discuss a recently proposed subgrid Lagrangian model capable of reproducing the effect of unresolved eddies on single particle dynamics (absolute dispersion) as well as on the relative separation of tracers. The model is simple, computationally efficient and is capable to reproduce Richardson separation dynamics between pairs in a cloud composed by an arbitrary number of tracers [3].

[1] Scatamacchia, R., Biferale, L. & Toschi, F. (2012). Extreme events in the dispersions of two neighboring particles under the influence of fluid turbulence. Physical Review Letters, 109(14):144501. [2] Biferale, L., Lanotte, A.S., Scatamacchia, R. & Toschi, F. (2014). Intermittency in the relative separations of tracers and of heavy particles in turbulent flows. Journal of Fluid Mechanics, 757, 550-­‐ 572. [3] Mazzitelli, I.M., Toschi, F. & Lanotte, A.S. (2014). An accurate and efficient Lagrangian sub-­‐grid model. Physics of Fluids, 26(9), 095101-­‐1/17.

Bio: 
Professor Federico Toschi holds the chair of Computational Physics of Multi-­‐scale Transport Phenomena in the department of Physics and in the Department of Mathematics and Computer Science at Eindhoven University of Technology. The CPMTP section has recently been established within the 3TU Centre of Excellence for Multiscale Phenomena. His research interests include fluid dynamics turbulence, statistical physics, micro and nano-­‐fluids, numerical methods for fluid dynamics, high-­‐performance computing. The focus of his current research are multi-­‐scale problems related to the physics of fluid studied by means of state-­‐of-­‐the-­‐art computational models. He has been awarded large scale computational grants (DEISA Extreme Computing Initiative, PRACE) to study the dynamics of heavy particles in turbulence and hemodynamics. He is the founder and administrator of the International CFD Database hosted at CINECA (Bologna, Italy), http://cfd.cineca.it. He served as chairman of the International Collaboration for Turbulence Research (ICTR, http://www.ictr.eu). He acted as Chair of the COST Action MP0806 on "Particles in turbulence" and is currently chair of the COST Action MP1305 "Flowing matter”.