Living and Inanimate Closer Than It Seems

Blood, lymph, and other biological fluids possess remarkable and sometimes intricate properties. Many of these biological solutions are Non-Newtonian liquids, which exhibit a nonlinear relationship between voltage and deformation, causing unexpected behaviors. For instance, some of these unusual fluids deform easily with a light touch but become almost solid when subjected to strong force.

One unique characteristic of biological solutions is elastic turbulence, which refers to the chaotic movement of fluids occurring when polymers are present in small concentrations in aqueous solutions. Such turbulence is exclusive to Non-Newtonian liquids.

While classical turbulence is observed in Newtonian fluids like water, which flows smoothly past a bridge support, mathematical theories that describe and predict classical turbulence are already established. However, tools to understand elastic turbulence, despite its significance in biological and industrial settings, are not yet developed.

“This phenomenon is crucial in microelectronics, especially during the mixing of small amounts of polymer solutions, which can be challenging due to a very uniform flow,” explains Professor Marco Edoardo Rosti, the leader of the complex fluids and flows research group.

Recent research published in the journal Nature Communications could reshape the understanding of elastic turbulence. Scientists from OIST working with researchers from TIFR in India and Nordita in Sweden demonstrated that elastic turbulence has more similarities with classical Newtonian turbulence than previously believed.

“Our findings reveal that elastic turbulence follows a universal law of energy dissipation and displays previously undiscovered intermittent behavior. These insights provide a fresh perspective on the phenomenon of elastic turbulence,” explains Professor Rosti. In analyzing the flow, scientists commonly utilize the velocity field. “By examining the distribution of velocity fluctuations, we can make statistical predictions about the flow,” says Dr. Rahul K. Singh, the first author of the publication.

When investigating classical Newtonian turbulence, researchers measure velocity across the flow and calculate the velocity differences between two points to establish a velocity gradient. “In this study, we measure the velocity at three points and calculate the second differences. Initially, the first difference is calculated by subtracting the fluid velocities measured at two distinct points. Subsequently, two such first differences are subtracted to obtain the second difference,” explains Dr. Singh.

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