Fully developed turbulence is one of the big unsolved problems in fluid dynamics, so much so that Richard Feynman described turbulence as the most important unsolved problem of classical physics. The main question is the distribution of rare events, which has important implications for, e.g., flight safety. Turbulence has been studied theoretically, numerically, and experimentally for roughly a 100 years. Still there are many open questions that we try to answer. Below we list the different faces of turbulence.
Turbulence in nature and industry often has objects in it, think of sand in rivers, fuel drops in combustion engines, chemical reactors, steam engines, animals swimming in water etc. These objects can roughly be summarised as bubbles, droplets, and particles, which all fundamentally modify turbulence. Not only is the spectrum different also the dispersion of these inclusions are changed. Note that these inclusions act on the flow, and vice versa, making the problem exceedingly complex and hard to study.
Using numerics and experiments we can look at 'pure' turbulence i.e. single phase flow with high Reynolds number. Numerically one can look at turbulence without any boundaries or objects and find relations. These fundamental studies are necessary for e.g. finding closures for modelling purposes. See also the sections below.
Our groups have also studied turbulence in the so-called Lagrangian point of view. i.e. one follows the flow, rather than measuring a flow at a fixed position (Eulerian approach). These findings give deep insight into the dynamics of particles and bubbles in flows.
Our research is not limited to purely fundamental research. We, for example, look at the turbulence in and around wind farms, at heat transfers in oceans, planets, and atmosphere among many other topics. We also look into the heat and mass transfer of turbulent flows which is very relevant for e.g. chemical reactions.