The question of how particles and droplets can grow in a turbulent environment is of great current interest in many fields, in astrophysics, cloud microphysics, in biology, and in the engineering sciences. For example, coagulation and condensation in turbulent clouds turn microscopic cloud droplets into rain drops. In astrophysics, planetesimals are thought to form by aggregation of microscopic dust grains in the turbulent environment surrounding a forming star. In both cases, turbulence is believed to be a crucial factor for particle growth. Yet the microscopic mechanisms determining this growth are far from understood. In the past few years there has been substantial progress in understanding the mechanisms that determine how particles move in turbulence, through experiments, numerical simulations, and the analysis of statistical models. The challenge is now to understand how and under which circumstances these mechanisms may lead to or prevent particle growth in turbulence. The program is aimed at scientists interested in the dynamics and the growth particles in turbulence, applications in the atmospheric sciences, astrophysics & engineering, or the mathematical analysis of these phenomena.
Themes and preliminary program schedule
We intend to organize the program around the following themes:
The focus of week one is to formulate and analyse models for particle aggregation, fragmentation, and erosion in turbulence that take into account fluctuations, and their applications in astrophysics.
During the first week we also intend to discuss recent progress and open questions in the mathematical analysis
of statistical models for particles in turbulence. Week two, in this preliminary schedule, is dedicated to
cloud-microphysics, to models for the droplet-size distribution that incorporate different mechanisms such as local thermodynamics, radiative cooling, but also the intermittency of turbulent fluctuations where necessary, and the inhomogeneity of the system.
Week three concerns non-spherical particles, their dynamics and interactions in turbulence. Important topics are the dynamics of ice crystals settling in turbulent clouds, and also the dynamics of plankton in the turbulent ocean, their feeding rates for example, and more generally the survival
strategies of small organisms and smart particles in turbulence.
Key topics for
for week four include the effect of hydrodynamic interactions and fluid inertia upon the dynamics of passive and active particles in fluids,
their collisions, as well as models for and measurements of collision and coalescence efficiencies.
- Statistical models for aggregation in turbulence (week 1)
- Condensation and coagulation in clouds (week 2)
- Non-spherical particles in turbulence (week 3)
- Collision dynamics of particles in fluids (week 4)
We expect many participants to stay for longer than just a week. The aim is to initiate interdisciplinary collaborations. The above schedule is therefore just a rough suggestion, and its details may change depending on the availability of participants.
We aim at having two or three 30-minute presentations per day during the mornings, and free time for discussions and project work during the afternoons. There will be plenty of time for discussions in a relaxed atmosphere.
Within the Wallenberg project Bottlenecks
in turbulent aerosols we intend to organise a shorter international meeting on Particles in Turbulence . We will coordinate this meeting with this Nordita program. Tentative dates are May 27-29, three days with shorter talks on particles in turbulence, APS format. Details will be announced here during the fall of 2019.
Nordita, Stockholm, Sweden
If you want to apply for participation in the program, please fill in the application form. You will be informed by the organizers shortly after the application deadline whether your application has been approved. Due to space restrictions, the total number of participants is strictly limited. (Invited speakers are of course automatically approved, but need to register anyway.)
Application deadline: extended to 30 November 2019
A minimum stay of one working week is required and we encourage participants to stay for a period of at least two weeks.
There is no registration fee.
PhD students and young Postdoc fellows are eligible for travel grants to participate in the program. If you are interested in such a grant, please mark the corresponding field in the application form, briefly summarize your interest in the program in the comments field, and indicate an estimation of your expected travel expenses. Since only a limited number of grants is available, decision concerning the grants will be made on a case-by-case basis and you will be notified shortly after the application deadline.
Nordita provides a limited number of rooms in the Stockholm apartment hotel BizApartments free of charge for accepted participants.
Please be aware that unfortunately, scammers sometimes approach participants claiming to be able to provide accommodation and asking for credit card details. Please do not give this information to them. For successful applicants, Nordita will be in touch via email regarding accommodation. If you are in any doubt about the legitimacy of an approach, please get in contact with the organisers.