Viscoelasticity-Induced Transitions in Active Turbulence

This study explores the impact of viscoelasticity on turbulence in active systems. Active particles, such as microorganisms like amoebae, bacteria, microtubules, and synthetic colloids, can induce turbulence motion through self-propulsion.Microbial suspensions can exhibit self-sustained turbulence which is a fascinating example of how simple life forms can collectively generate complex fluid dynamics, with important implications for mixing and molecular transport. Suspended particles in a viscoelastic fluid show complex flow patterns because of the interplay between fluid elasticity and particle dynamics. By employing continuum models and computational simulations, we analyze how viscoelasticity influences critical aspects of active fluid turbulence, including energy spectra, velocity distribution, and flow anisotropy. Our approach integrates the Toner-Tu-Swift-Hohenberg (TTSH) model for active fluids with the Oldroyd-B model for viscoelastic media. Viscoelastic effects are diabolical for active turbulence, either soothing or stirring it, depending on whether activity levels are below or above the critical activity. We have further examined how increasing the activity of the fluid alters flow structure in viscoelastic fluids compared to active fluids. These findings provide new insights into the mechanisms of active turbulence in non-Newtonian fluids, impacting the understanding of biological processes and the design of systems where turbulence control is crucial