Unveiling the Intriguing Connection Between Elastic and Newtonian Turbulence

Blood, lymph fluid, and other biological liquids can exhibit unique and sometimes perplexing properties. Many of these biological solutions are classified as non-Newtonian fluids, characterized by a non-linear stress and strain relationship, behaving unexpectedly for a liquid. For instance, some fluids deform easily with light touch but act as solids when subjected to significant force.

One of these peculiar properties is elastic turbulence, describing the chaotic fluid motion induced by adding polymers in low concentrations to watery liquids. This type of turbulence is specific to non-Newtonian fluids, with polymers in the fluid behaving like micro springs, stretching and contracting within the flow. The significance of understanding elastic turbulence extends to microfluidic applications where mixing polymeric solutions can be challenging due to smooth flow.

Previously, elastic turbulence was deemed fundamentally different from classical turbulence found in Newtonian fluids, such as in rivers. However, recent research collaboration between the Okinawa Institute of Science and Technology Graduate University, TIFR in India, and NORDITA in Sweden, published in Nature Communications, suggests an unexpected similarity between elastic and Newtonian turbulence.

The study led by Professor Marco Edoardo Rosti reveals universal power-law decay of energy in elastic turbulence and an unanticipated intermittent behavior, shedding new light on the phenomenon. Utilizing advanced supercomputers, the research team delved into the intricacies of flow dynamics, uncovering that the velocity field in elastic turbulence displays intermittent patterns, a surprising finding challenging previous assumptions.

Dr. Rahul K. Singh, the lead author of the publication, explains the methodology employed in measuring velocity fluctuations to discern statistical predictions about flow, drawing parallels between classical Newtonian turbulence and elastic turbulence. The researchers’ detailed simulations unveiled that velocity fields in elastic turbulence exhibit intermittent fluctuations akin to an electrocardiogram signal.

The concept of intermittency in flow, traditionally associated with high-speed turbulence, was unexpectedly observed at low flow speeds in elastic turbulence, enhancing the understanding of the physics involved. These findings not only advance the comprehension of low-velocity turbulence but also lay the groundwork for future mathematical theories elucidating elastic turbulence, pivotal for predicting flow behavior and optimizing applications in mixing liquids.