About

Turbulence is ubiquitous in nature and so is its ability to form interfaces and promote mixing and dispersion of species across them. Sharp and strongly convoluted turbulence interfaces exist at the edges of free-shear flows such as effluent jets from waste-water outlets, atmospheric boundary layers and wakes of aircrafts. Interfaces appear at the boundaries of clouds in the atmosphere or in stratified flows in the ocean and lakes or between turbulent river flow and its sediment bed and they have a major importance on the flow dynamics because of their impact on transport of mass, heat and momentum.

Over the last decade, major progress has been made in understanding of turbulent-nonturbulent interfaces (TNTI, Da Silva et al. , 2014) through a combination of laboratory experiments, numerical simulation and theory. Many features of the TNTI have been uncovered about its small-scale properties (e.g. the structure of the TNTI) and its large-scale aspects (entrainment, self-similarity). However, despite the significant progress, our understanding remains incomplete and turbulent-nonturbulent interfaces remain a very active area of research.

The aim of this colloquium is to bring together scientists from a range of disciplines (fluid mechanics, turbulence, atmospheric and oceanic sciences) to communicate the progress in this area and to identify the most pressing research topics for the next five years. The colloquium will cover:

1. Turbulent-nonturbulent interfaces in boundary layers, jets, plumes, gravity currents: geometry, scaling, internal structure and dynamics;
2. Internal interfaces in turbulence ;
3. Global intermittency in high-Reynolds number turbulence due to turbulent-nonturbulent transitions (stably stratified boundary layers, evolution of patches of turbulence);
4. Mixing and passive/active scalars at sharp interfaces;
5. Turbulent/non-turbulent interface models .

The multi-disciplinary and informal nature of the colloquium will give significant scope for cross-fertilisation. The colloquium proposed here follows on from a highly successful workshop “the 1 ^st Multiflow conference on the Turbulent-Non-turbulent interface” that took place in Madrid in October 2012; the organisers taking part in the organisation of this colloquium also.