Researchers identify universal laws in the turbulent behavior of active fluids

Credit: Piotr Sidlecki/public domain
Active fluids are systems made up of bacteria and cellular tissues. Because their components can generate forces and move independently, they can spontaneously flow. The spontaneous flows can become chaotic if the activity level is too high. This is similar to the chaotic behavior of ordinary fluids. Researchers from the University of Barcelona have discovered universal laws that govern turbulent fluid behavior. Their research has been published in Physical Review X.

Because chaotic flows in active fluids resemble ordinary turbulence visually, they are called active turbulence. This phenomenon can be used to design nanomotors. It can also explain complex flows in living systems such as wound closures. The UB researchers claim that their research "is relevant" because it shows that active turbulence flows, despite being complex and chaotic, can be described using simple and general mathematical laws.

They used active fluids made of cytoskeletal proteins, enzymes and other energy sources to create forces and flow naturally. Researchers from the institutes of UB, UBICS, and IN2UB created a thin layer this active material that was surrounded by two passive fluids, water and oil.

Thanks to fluorescent tracers, the video captures the chaotic flow in an active pneumatic. Credit: B. Martinez-Prat et al. Phys.Rev. Phys.Rev.

The researchers also measured fluid flows in active fluids and confirmed experimentally two flow regimes they had predicted theoretically. The experiments also revealed a new flow regime due to the coupling between the active layer and the surrounding passive fluids. This study highlights the importance of passive fluids around the active system. The researchers developed a theoretical framework to explain the results. It considers the effects of passive fluids and predicts the power laws that were observed in the experiments.

Continue reading Researchers reveal the universal properties and functions of active turbulence

More information: Berta Martnez -Prat et., Scaling Regimes for Active Turbulence With External Dissipation. Physical Review X (2021). Information from the Journal: Physical Review X Berta Martnez Martnez-Prat et al., Scaling Regimes for Active Turbulence With External Dissipation. (2021). DOI: 10.1103/PhysRevX.11.031065