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Gottingen, Germany

The Max Planck Institute for Dynamics and Self-Organization in Göttingen, Germany, is a research institute for investigations of complex non-equilibrium systems, particularly in physics and biology.Its founding history goes back to Ludwig Prandtl who in 1911 requested a Kaiser Wilhelm Institute to be founded for the investigation of aerodynamics and hydrodynamics. As a first step the Aeronautische Versuchsanstalt was established in 1915 and then finally the Kaiser Wilhelm Institute for Flow Research was established in 1924. In 1948 it became part of the Max Planck Society. The Max Planck Society was founded in this institute. In 2003 it was renamed to Max Planck Institute for Dynamics and Self-Organization. It is one of 80 institutes in the Max Planck Society . Wikipedia.

Martens E.A.,Max Planck Institute for Dynamics and Self-Organization
Chaos | Year: 2010

We study a network of three populations of coupled phase oscillators with identical frequencies. The populations interact nonlocally, in the sense that all oscillators are coupled to one another, but more weakly to those in neighboring populations than to those in their own population. Using this system as a model system, we discuss for the first time the influence of network topology on the existence of so-called chimera states. In this context, the network with three populations represents an interesting case because the populations may either be connected as a triangle, or as a chain, thereby representing the simplest discrete network of either a ring or a line segment of oscillator populations. We introduce a special parameter that allows us to study the effect of breaking the triangular network structure, and to vary the network symmetry continuously such that it becomes more and more chain-like. By showing that chimera states only exist for a bounded set of parameter values, we demonstrate that their existence depends strongly on the underlying network structures, and conclude that chimeras exist on networks with a chain-like character. © 2010 American Institute of Physics. Source

Seiden G.,Max Planck Institute for Dynamics and Self-Organization | Seiden G.,Weizmann Institute of Science | Thomas P.J.,University of Warwick
Reviews of Modern Physics | Year: 2011

Rotating-drum flows span a variety of research areas, ranging from physics of granular matter through hydrodynamics of suspensions to pure liquid coating flows. Recent years have seen an intensified scientific activity associated with this unique geometrical configuration, which has contributed to our understanding of related subjects such as avalanches in granules and segregation in suspensions. The existing literature related to rotating-drum flows is reviewed, highlighting similarities and differences between the various flow realizations. Scaling laws expressing the importance of different mechanisms underlying the observed phenomena have been focused on. An emphasis is placed on pattern formation phenomena. Rotating-drum flows exhibit stationary patterns as well as traveling and oscillating patterns; they exhibit reversible transitions as well as hysteresis. Apart from the predominant cylindrical configuration, this review covers recent work done with tumblers having other geometries, such as the sphere and the Hele-Shaw cell. © 2011 American Physical Society. Source

Lohse D.,University of Twente | Lohse D.,Max Planck Institute for Dynamics and Self-Organization | Zhang X.,University of Twente | Zhang X.,RMIT University
Reviews of Modern Physics | Year: 2015

Surface nanobubbles are nanoscopic gaseous domains on immersed substrates which can survive for days. They were first speculated to exist about 20 years ago, based on stepwise features in force curves between two hydrophobic surfaces, eventually leading to the first atomic force microscopy (AFM) image in 2000. While in the early years it was suspected that they may be an artifact caused by AFM, meanwhile their existence has been confirmed with various other methods, including through direct optical observation. Their existence seems to be paradoxical, as a simple classical estimate suggests that they should dissolve in microseconds, due to the large Laplace pressure inside these nanoscopic spherical-cap-shaped objects. Moreover, their contact angle (on the gas side) is much smaller than one would expect from macroscopic counterparts. This review will not only give an overview on surface nanobubbles, but also on surface nanodroplets, which are nanoscopic droplets (e.g., of oil) on (hydrophobic) substrates immersed in water, as they show similar properties and can easily be confused with surface nanobubbles and as they are produced in a similar way, namely, by a solvent exchange process, leading to local oversaturation of the water with gas or oil, respectively, and thus to nucleation. The review starts with how surface nanobubbles and nanodroplets can be made, how they can be observed (both individually and collectively), and what their properties are. Molecular dynamic simulations and theories to account for the long lifetime of the surface nanobubbles are then reported on. The crucial element contributing to the long lifetime of surface nanobubbles and nanodroplets is pinning of the three-phase contact line at chemical or geometric surface heterogeneities. The dynamical evolution of the surface nanobubbles then follows from the diffusion equation, Laplace's equation, and Henry's law. In particular, one obtains stable surface nanobubbles when the gas influx from the gas-oversaturated water and the outflux due to Laplace pressure balance. This is only possible for small enough surface bubbles. It is therefore the gas or oil oversaturation ζ that determines the contact angle of the surface nanobubble or nanodroplet and not the Young equation. The review also covers the potential technological relevance of surface nanobubbles and nanodroplets, namely, in flotation, in (photo)catalysis and electrolysis, in nanomaterial engineering, for transport in and out of nanofluidic devices, and for plasmonic bubbles, vapor nanobubbles, and energy conversion. Also given is a discussion on surface nanobubbles and nanodroplets in a nutshell, including theoretical predictions resulting from it and future directions. Studying the nucleation, growth, and dissolution dynamics of surface nanobubbles and nanodroplets will shed new light on the problems of contact line pinning and contact angle hysteresis on the submicron scale. © 2015 American Physical Society. © 2015 American Physical Society. Source

Monteforte M.,Max Planck Institute for Dynamics and Self-Organization
Physical Review Letters | Year: 2010

We demonstrate deterministic extensive chaos in the dynamics of large sparse networks of theta neurons in the balanced state. The analysis is based on numerically exact calculations of the full spectrum of Lyapunov exponents, the entropy production rate, and the attractor dimension. Extensive chaos is found in inhibitory networks and becomes more intense when an excitatory population is included. We find a strikingly high rate of entropy production that would limit information representation in cortical spike patterns to the immediate stimulus response. © 2010 The American Physical Society. Source

Herminghaus S.,Max Planck Institute for Dynamics and Self-Organization
Physical Review Letters | Year: 2012

The wetting properties of solid substrates with mesoscale (between van der Waals tails and the capillary length) random roughness are considered as a function of the microscopic contact angle of the wetting liquid and its partial pressure in the surrounding gas phase. It is shown that the well-known transition occurring at Wenzel's angle is accompanied by a transition line at which a jump in the adsorbed liquid volume occurs. This should be present generally on surfaces bearing homogeneous, isotropic random roughness. While a similar abrupt filling transition has been reported before for certain idealized groove or trough geometries, it is identified here as a universal phenomenon. Its location can be analytically calculated under certain mild conditions. © 2012 American Physical Society. Source

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