Name: Dynamics of Particles in Flows: Fundamentals and Applications
Start: 2014-06-02T09:00:00+02:00
End: 2014-06-27T18:00:00+02:00
Location: Albanova, Stockholm

Monday, 2 June 2014
10:00 Clustering of swimming phytoplankton in turbulence - Guido Boffetta (University of Torino)
Clustering of swimming phytoplankton in turbulence
- Guido Boffetta (University of Torino)
10:00 - 10:45
Room: NORDITA seminar room
Tuesday, 3 June 2014

09:00 Joint Activity: Modelling of Fibre Suspension Flows
Joint Activity: Modelling of Fibre Suspension Flows
09:00 - 18:00
Room: Lecture Room FR 4
Wednesday, 4 June 2014

09:00 Joint Activity: Modelling of Fibre Suspension Flows
Joint Activity: Modelling of Fibre Suspension Flows
09:00 - 11:50
Room: FB 52
Thursday, 5 June 2014
09:30 Entrainment and mixing at the edge of a cloud - Joerg Schumacher (TU Ilmenau, Germany)
Entrainment and mixing at the edge of a cloud
- Joerg Schumacher (TU Ilmenau, Germany)
09:30 - 10:30
Room: FB 52 Responses of a droplet ensemble during initial entrainment and subsequent mixing of cloudy and clear air at the edge of a cloud are studied by 3d DNS which combine the Eulerian description of the turbulent velocity, temperature and vapor content fields with a Lagrangian ensemble of cloud water droplets. We discuss their size distribution, the supersaturation and the mixing properties. Furthermore we give an outlook of how these data might be matched to large eddy simulation which cover a whole cloud or clusters of clouds.
10:30 Aggregation, diffusion, and rheology in particulate suspensions at continuum scale - Antti Puisto (Aalto University)
Aggregation, diffusion, and rheology in particulate suspensions at continuum scale
- Antti Puisto (Aalto University)
10:30 - 11:30
Room: FB 52 In this presentation we will discuss the modeling of aggregation and diffusion of particles under shear flow at continuum scale using population balance based models. First, we will concentrate on aggregation colloidal suspensions, specifically modeling the state of fractally growing aggregates, and its implications to the rheology of the fluid - for both orthokinetic and perikinetic aggregation [1]. Furthermore, we will discuss the consequences of such thixotropy caused by time-dependent aggregation to the rheological characterization of the fluid. Then, we turn the discussion to hard sphere suspensions. For these we have studied shear induced migration of particles [2] in simple geometries, and its influence on the experimentally measured flow curves. With repulsive wall-particle interaction we observe the appearance of shear rate dependent depletion layers near the device walls [3]. For long time, in structured fluids this has been modeled on sub-particle length scales, however, here we show slip-layers of several tens of particle diameters, comparable to experimental data observed, for instance, in stabilized emulsions [4]. Furthermore, we will discuss the influence of this wall depletion to the globally measured rheology. [1] M. Mohtaschemi et al. Soft Matter 10, 2971 (2014). [2] R. J. Phillips et al. Phys. Fluids A 4, 30 (1992). [3] M. Korhonen et al. Under preparation (2014). [4] S. Manneville et al. Eur. Phys. J. E 10, 209 (2003).
14:00 Advection of Active Particles - Nick Ouellette (Yale)
Advection of Active Particles
- Nick Ouellette (Yale)
14:00 - 14:45
Room: FB 52
16:00 Motion of fluid particles and the irreversibility of turbulence - Haitao Xu (University of Gottingen)
Motion of fluid particles and the irreversibility of turbulence
- Haitao Xu (University of Gottingen)
16:00 - 17:00
Room: FB 52 In fluid turbulence, there is a wide separation between the scales at which the fluid is forced into motion and the scales at which the dissipation dominates. In between, energy is transferred through scales. This energy cascade dictates that turbulence statistics are not time-reversible, as reflected in the celebrated Karman-Howarth-Kolmogorov equation, which relates the energy flux with velocity differences in space (Eulerian statistics). This can be further extended to statistics along trajectories of fluid particles in turbulence (Lagrangian statistics). The energy flux can also be related to the relative motion between fluid particles. The interesting question is then: Can one detect irreversibility from the motion of single fluid particles, where an intrinsic length scale is missing? Using data from both experiments and direct numerical simulations in a large set of flow conditions, we show that the irreversibility induced by the energy flux through spatial scales can be revealed and quantified by following the change of the kinetic energy of single fluid particles. We find that fluid particles decelerate harder than they accelerate, i.e., they tend to lose kinetic energy faster than they gain it. The third moment of the power fluctuations along a trajectory, nondimensionalized by the energy flux, displays a remarkable power law as a function of the Reynolds number, both in two and in three spatial dimensions. This establishes a relation between the irreversibility of the system and the range of active scales.
Friday, 6 June 2014
Saturday, 7 June 2014
Sunday, 8 June 2014