

Group photos.
The main organizers were Marc Keßeböhmer, Ivan Ovsyannikov, Jens Rademacher, and the scientific committee also included Marc Avilla (Zarm, University of Bremen), Gualtiero Badin (University of Hamburg) and Marcel Oliver (Jacobs University Bremen). The event was mainly sponsored by the Transregional Collaborative Research Center TRR 181 “Energy Transfers in Atmosphere and Ocean”, funded by the the German Research Foundation.
The Winter School in 2018 was the 6th annual event in the series held at the University of Bremen, with around 65 international participants coming from Austria, Canada, Denmark, France, Germany, Iceland, Spain, Sweden, Switzerland, UK and USA. The event consisted of mini-course lectures, research talks, exercise sessions, a poster session and a public lecture. Further details can be found below and on the Winter School webpage.
Sergey Chernyshenko and Paul Manneville and their respective mini-courses.
Dwight Barkley and Hans Burchardt with their mini-course lectures.

Exercise session by Giovanni Fantuzzi.
The timetable was organized in the way that the morning sessions were used for mini-course lectures and the afternoon sessions were occupied with exercise sessions and research talks. Mini-courses consisted of three 90-minutes lectures and one 30-minutes exercise session. The research talks were 60 or 30 minutes long. Mini-courses and talks together introduced the theoretical background and demonstrated the latest research achievements on the topic of turbulence.
Kai Schneider and Genevieve Brett giving research talks.
The main lectures were the following: “Recent advances in the subcritical transition to turbulence” by Dwight Barkley, “Turbulence closure modelling in the coastal ocean: the essential effect of stable stratification on vertical mixing” by Hans Burchard, and “The problem of turbulence: bounding solutions to equations of fluid mechanics and other dynamical systems” by Sergey Chernyshenko, with two exercise sessions given by Giovanni Fantuzzi and “Spatiotemporal chaos” by Paul Manneville.
The research talks were held by Thomas Boeck, Genevieve Brett, Björn Hof, Ana Maria Mancho, Francesco Ragone, Kai Schneider, Lennaert van Veen and Michael Wilczek.
A special highlight of the week was the public lecture “How pipe flow becomes turbulent - a matter of life and death” by Björn Hof at the Bremen "House of Science" (Haus der Wissenschaft). One of the main ideas was that turbulent puffs may appear in a pipe spontaneously, but for some parameter values they may disappear after some time and for other - give rise to new ones, such that the flow becomes constantly turbulent. The lecture was accompanied by a simple experiment in which the transition from laminar to turbulent flow was easily visible on the water jet flowing out of the pipe.

Björn Hof during his public lecture setting up an experiment.
All the Winter School participants were encouraged to present a poster at a special poster session. The posters were available for viewing the whole week.
Discussions during the poster session.
The social program included the walk through the famous Bremen Bürgerpark and a guided tour of the city centre. The conference dinner took place at Ratskeller, the restaurant below the Old Rathaus building.
The Winter School participants walking through the Bremen Bürgerpark and the city center.
The conference dinner at the Bremen Ratskeller.