Theo Driessen - PhD

Michiel Hinsberg - PhD

Florian Janoschek - PhD

Riccardo Scatamacchia - PhD

Sudhir Srivastava - PhD

Francesca Tesser - PhD

Michiel Hinsberg - PhD

Florian Janoschek - PhD

Riccardo Scatamacchia - PhD

Sudhir Srivastava - PhD

Francesca Tesser - PhD

Francesco Picano

Luca Biferale

Visiting professor from 01-01-2011 to 31-12-2011

Cascade 3.19, tel. 4851

Enrico Calzavarini

HPC-Europa Grant

Visit from 01-07-2010 to 32-09-2010

Salvatore Lovecchio

HPC-Europa Grant

Visit from 1-6-2011 to 31-8-2011

Eros Pecile

Erasmus student

Visit from 31-05-11 to 31-09-11

Supervisor: Federico Toschi

Alessandro Dal Cin

Visit from 07-03-2010 to 28-01-2011

Riccardo Scatamacchia

Visit from 07-02-2011 to 07-03-2011

Luca Scarbolo

HPC-Europa Grant

Visit from 22-09-2010 to 22-12-2010

Andrea Donini

Currently working at the Mechanical Engineering Department

WH 3.125, tel. 3621

Alessandro Candini

Francesca Mancini

Enrico Piton

Andrea Scagliarini

**June 17, 2013 — June 21, 2013**

Coordinators:

**Cristian Marchioli** (Università di Udine, Italy)

**Federico Toschi** (Eindhoven University of Technology, The Netherlands)

Dynamics of non-spherical particles and aggregates in fluid flow are encountered both in nature and in industrial applications. Examples for non-spherical particles include airborne solid particles or aerosols, carbon nanotubes, micro-organisms like phytoplankton, sediment-laden flows and wood-fibre suspensions. Particle aggregates are found in chemical, industrial or material processes for colloids and in polymer manufacturing. In these processes, particle size ranges from several nanometers to several centimeters, with loadings that may substantially change the macroscopic (rheological) properties of the suspension flow. On the other hand, transport and interaction of particles/aggregates in complex (e.g. turbulent) flows is governed by a number of physical processes occurring at a wide range of different scales. The rapidly increasing computational power has recently made feasible three-dimensional, time-dependent simulations of non-ideal particles in fluid flows, producing an entire branch of flourishing literature which is fostering research in dispersed multiphase flow. Progress has been substantial also from an experimental viewpoint, with improved measurement techniques based on optics or magnetic resonance flow imaging. Due to the multiscale nature of the problem, investigation and modelling require synergetic use of such approaches.

Objective of the course is to provide a general and unified frame of the current research on the dynamical behaviour of non-spherical particles and particle aggregates in complex flows and put future research paths in perspective. The focus will be on generic aspects and physics of non-ideal particle suspensions (e.g. rheological properties in suspensions of anisotropic deformable particles, and modulation of turbulence induced by particles/aggregates). Issues related to modelling and physical understanding at all various length scales will be covered: from the scale resolving the complex flow around individual non-spherical particles, to large eddy simulation models for flows with particles, to large-scale Eulerian-Eulerian models. Among the topics to be included are particle dynamics in free and wall-bounded turbulence, fluid-particle interactions, collision modelling, break-up and agglomeration, advances in measurement and simulation techniques, and rheological modelling.

The lectures will also provide a wide overview of cutting-edge work in this very active area of multiphase flow research and focus in more detail on a few advanced topics of significant practical and theoretical value in several areas of engineering and applied physics. This will reinforce understanding of the fundamental phenomena and their importance, providing participants with varied conceptual and methodological tools applicable to problems at hand. After the lectures, students should possess the necessary knowledge of the basic capabilities, potentials and limitations of the various numerical and experimental methods taught and, hence, should be able to critically evaluate the reliability and accuracy of the information these methods can provide when applied to practical situations.

Please register on the website

**July 1, 2013 — July 5, 2013**

**Prof. dr. Federico Toschi** (Eindhoven University of Technology, Eindhoven)

**Prof. dr. Eberhard Bodenschatz** (Max Planck Institute for Dynamics and Self-Organization, Goettingen)

The transport, distribution and collisions of particles in turbulent flows is of fundamental interest, as well as being present in a variety of engineering and naturally occurring flows. Examples of related scientific challenges include rain formation in clouds, pollution dispersion in the atmosphere, emission reduction in combustion and plankton population dynamics. In such flows, particle inertia is an important parameter, but in many cases finite particle size and deformation play important roles. In most real life flows, the flow geometries are complex due to mixed forcing at various scales. This in addition to the complex relationship between large scale structures, intermittency and anisotropy at the small scales of motion in turbulence present us with a rare challenge increase the scope of our understanding, by systematically investigate complex flows from the numerical, theoretical and the experimental point of view.

The purpose of the conference is to bring together experts from various fields of turbulence research, exchange ideas and discuss new methodologies for addressing these challenging issues.

**Davide Picchi**

**Simone Fisci**

**Luca Biferale**

Visiting professor from 01-01-2011 to 31-12-2011

**Enrico Calzavarini**

HPC-Europa Grant

Visit from 01-07-2010 to 32-09-2010

**Salvatore Lovecchio**

HPC-Europa Grant

He will visit us from 1-6-2011 to 31-8-2011

Erasmus student, visiting from 31-05-11 to 31-09-11

Supervisor: Federico Toschi

Visit from 07-03-2010 to 28-01-2011

Visit from 07-02-2011 to 07-03-2011

**Luca Scarbolo**

HPC-Europa Grant

visit from 22-09-2010 to 22-12-2010

**fluids,**

** flowing across the scales **

Friday, June 24, at 4 p.m.

Fluids are everywhere and still many of their fundamental properties are not understood. The apparent simplicity of the equations describing the motion of simple fluids contrasts with the beautiful complexity of turbulence. Fluid dynamics is clearly important to our daily life: we drive, navigate and fly inside fluids. Fluids are also responsible for the transport of mass and heat, for example in the atmosphere, while fluids flowing inside our body provide the fundamental support for cell life. In recent years computers have added to experimental equipment to help disclose the phenomenology of fluid motions. In this lecture I will try to illustrate the beauty of the physics behind fluid flows and some of the research topics that are currently keeping me busy .

**July 9, 2012 — July 13, 2012**

Coordinators:

**Federico Toschi**(Eindhoven University of Technology, The Netherlands)**Adrian Muntean**(Eindhoven University of Technology, The Netherlands)

The collective motion of individuals (correlated motion of ants or migration of bacteria, flocks of birds, just to mention but a few) is a fascinating phenomenon capturing our attention. Besides the aesthetic aspects induced by such an expression of collective behavior, there are many crucial aspects of practical nature that attracted the interest of various scientific communities ranging from logistics, theoretical biology, and ecology to statistical physics and mathematics. On one hand, we wish to better understand, for instance, the formation of swimming patterns in large communities of fish to improve large scale fishing strategies. On the other hand, in congested flows, pedestrians display significantly different behaviors from those typical to situations when they are walking in free conditions. If panic situations occur, then small microscopic (individual-level) interactions can lead to disastrous macroscopic patterns (e.g. shock-like waves) leading to the jamming of a desired evacuation option or even to losses of human lives.

The aim of this school is to present, by means of 6 mini-courses, the state-of-the-art of the theoretical (statistical mechanics and mathematics) understanding of collective motions of crowds. The topics we include here are:

• Kinetic models for self-organized collective motion.

• Discrete and continuum dynamics of reacting and interacting

individuals.

• Finite-speed propagation models of chemo-tactic movements.

• Modeling with measures:

(i) Multiscale modeling of pedestrian motions by time-evolving measures;

(ii) Motions and interactions in heterogeneous domains.

• Handling contacts in pedestrian dynamics: On the concept of pressure.

Multiscale models in social (networks) applications, eventually combining mean-field and kinetic equations with either microscopic or macroscopic objects, are approaches of strongly increasing importance and high potential for future quantitative research. Typically, individual-based models need to be intelligently coarse-grained to translate the relevant microstructure information to a mesoscopic (Boltzmann-level) or to a macroscopic (continuum) level.

Relevant questions include: What is the natural scaling for the averaging? How much microstructure information needs to be kept to capture the specific individual-level interaction responsible for the formation and propagation of the macroscopically-observed pattern (for instance, lane formation in pedestrian counterflow). What are the main microscopic interactions responsible for the macroscopic cross-diffusion transport mechanism sometimes arising in pedestrian’s motion?

Within the frame of this school, we emphasize on one hand the role played by measure theory in deriving averaged equations, while on the other hand we show how measure theory can be used to prove rigorously the mean-field derivation of chemo-tactic movements, e.g. Numerical simulations of generic collective motions as well as experimental findings and simulations of pedestrian flows hosting macroscopic patterns will be pointed out.

The target audience of this summer school are graduate students, PhD candidates and young faculty members in mathematics, applied theoretical physics and biology, as well as (chemical, transportation, mechanical, ...) engineering having a strong research interest in understanding the multiscale complexity of the collective motion behavior. The participants are expected to have a good mathematical background. We hope that everybody will be willing to actively participate in both discussion and poster sessions.

KEYWORDS: Lanes and Flocks Formation, Social and Behavioral Sciences, Conservation laws, Micro and Macro Models, Mass Measures, Averaging, Social Networks, Initial and Boundary Value Problems.

Suspensions of small aggregates are found in many different situations, such as environmental, chemical, industrial or material processes for colloids, polymer manufacturing and aerosols. The control of small aggregates size distribution is a key question for the theoretical investigation, and more importantly for the processing of the suspensions. In turbulent fluid flows, the existence of a stationary mass distribution of such small aggregates is crucially linked to the properties of the flow (magnitude of the shear, shear distribution etc..). However, the role which is played by the turbulence is still the matter of investigation and debate.

The goal of this workshop is to gather experts in colloidal and non ideal particles suspensions, together with specialists of turbulent transport, to discuss about particles dynamics and statistics, and about the way aggregates breakup and coalesce in turbulent flows.

Alessandra S. Lanotte

Cosimo Elefante

Giovanni Lella

Fabio Massimo Grasso

(CNR Istituto di Scienze dell’Atmosfera e del Clima)

Luca Biferale (Dept. Physics, University of Tor Vergata, Rome, Italy)

Ulrike Feudel (Institut für Chemie und Biologie des Meeres, University of Oldenburg, Germany)

Alex Liberzon (School of Mechanical Engineering, Tel Aviv University, Israel)

Cristian Marchioli (Dipartimento di Energetica e Macchine-DIEM, University of Udine, Italy)

Federico Toschi (Technische Universiteit Eindhoven, The Netherlands)

MPNS COST Action MP0806 "Particles in Turbulence"

FPS COST Action FP1005 "Fibre suspension flow modelling"

**SCIENTIFIC CONTENT**

This six-week program (12 March 2012 to 20 April 2012) will focus on recent development in the understanding of fluid dynamics turbulence with the goal to identify promising breakthrough directions.

From the point of view of theoretical physics, turbulence is a classical field theory, out of equilibrium and in a strong coupling regime.

Turbulence is one of the great problems of classical physics still mainly unsolved. With turbulence we mean a physical state of a flow with many dynamically active variables and far from equilibrium. The first difficulty in theoretical approaches to turbulence consists in the large number of active degrees of freedoms. The scales where energy is injected is typically strongly separated from the scales where energy is dissipated. Non-linear interactions lead to a strong coupling between all degrees of freedoms. Energy transfer may be in average positive, leading to formation of small-scales fluctuations superposed to large scale structures or in average negative, leading to an accumulation of energy at larger and larger scales. Moreover, fluctuations around the mean can be Gaussian or strongly intermittent, depending on the direction of the energy cascade and on the dimensionality of the system. The situation is complicated in presence of active scalar fields, like for the case of thermal convection, active vector fields, as in magnetohydrodynamics and/or by the presence of boundaries, where also a net transfer of momentum is established in the system. The Lagrangian point of view, measuring underlying fluid velocity riding tracers or inertial particles, point-like or with a finite size, is also crucial to control statistical properties at different frequencies.

Among the questions that will be address during the program we cite: is the energy cascade in isotropic turbulence universal? What are the corrections expected in presence of large scale anisotropy? What happens if external or internal mechanism breaks parity invariance? What happens at changing the embedding dimensionality? Can we improve sub grid modeling by a better understanding of the energy cascade mechanism? What are the effects of strong active fields, like in thermal convection and MHD? Are large scale structures universal in these latter cases? What are the statistical connections between Eulerian and Lagrangian descriptions. Can 2d and 3d physics coexist? Can we smoothly change from a 2d to a 3d systems? What about turbulence in 1d turbulence (Burgers equations) in 0d (Shell Models) in larger and larger dimension or even in non-integer dimensions?

A partial answer to even only a small sub-set of these questions will require important synergies between scientists from theory, numerics and experiments and would qualify the program as big success.

The program will be organised in "focused" weeks concerning one or two of the above topics.

**TENTATIVE PROGRAM**

12/03-18/03 : sub-grid modeling, wall bounded flows, Non Newtonian flows.

19/03-25/03 : 2d and 3d systems. Turbulence in rotating systems; Geophysical flows.

26/03-01/04 : Lagrangian and Eulerian turbulence.

02/04-06/04 : INTERNATIONAL CONFERENCE.

07/04-13/04 : Thermal convection & Magnetohydrodynamics.

14/04-20/04 : Turbulence modeling and theory.

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