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A long-standing challenge in physics

Turbulence is everywhere, from atmospheric flows to industrial systems, yet it remains notoriously difficult to predict and control. A key feature of turbulence is that small-scale fluctuations tend to behave universally, largely independent of the large flow.

While this property may simplify modeling, it also suggests that controlling turbulence at small scales may be nearly impossible. De Wit’s work challenges this idea by showing that these small-scale dynamics can, in fact, be influenced in targeted ways.

Using particles to calm turbulent flows

In the first part of his research, De Wit studied turbulent flows filled with light, actively driven particles, such as tiny bubbles. These particles do not spread randomly: they concentrate in regions of intense swirling motion, which are closely linked to the strongest fluctuations in turbulence.

By carefully controlling how these particles are forced, De Wit demonstrated that they can alter the structure and statistical properties of the flow itself. In particular, the particles can reduce the intensity of the most extreme, intermittent fluctuations—effectively calming the turbulence at small scales.

This work highlights how interactions between particles and fluid motion can create collective effects that reshape even the behavior of a chaotic system.

Breaking symmetry in exotic fluids

The second part of the thesis explores a more unconventional route: modifying the fluid itself. De Wit investigated chiral fluids, in which the microscopic building blocks have a preferred rotation, breaking a fundamental symmetry known as parity.

Such fluids exhibit odd viscosity, an unusual property that changes how momentum is transported without dissipating energy. The results show that this property can dramatically alter turbulence:

• energy transfer between scales is fundamentally reshaped
• the flow can self-organize into striking patterns
• a new regime emerges, dominated by wave-like interactions

At the same time, these modifications reduce the strong, erratic fluctuations typical of ordinary turbulence.

Toward controlled turbulent systems

Together, these findings demonstrate that turbulence is not an immutable phenomenon. By either introducing tailored particles or engineering fluids with specific microscopic properties, it is possible to influence how energy flows through the system and suppress its most extreme behavior.

This opens new possibilities for controlling turbulence in applications ranging from industrial processes and energy systems to environmental flows, while also advancing the fundamental understanding of complex, out-of-equilibrium physics.

A new perspective on a classic problem

By challenging one of the core assumptions of turbulence theory, De Wit’s work provides a fresh perspective on a problem that has puzzled scientists for decades. His results show that even in one of physics’ most chaotic systems, order and control can be introduced, if we know where to look.