Active turbulence, a complex organization of matter driven at the scale of its constituent agents, is confounding. Particularly, analogies with high Reynolds number, inertial (Kolmogorov) turbulence have not survived beyond the qualitative. The lack of scale separation in low Reynolds active flows breaks away from the familiar notions of the energy cascade and approximate scale-invariance of inertial turbulence. So do experimental studies hinting that active turbulence can manifest anomalous diffusion, while inertial turbulence does not surpass classical diffusion. Using a continuum hydrodynamic model for bacterial turbulence, we investigate the Lagrangian and Eulerian features distinguishing active from inertial turbulence. We find the emergence of robust superdiffusion, intermittency, universality and maximal chaos beyond a critical level of activity. This makes the phenomenology of active turbulence rich and riddled with surprising nuances, which at times bridge the analogy with inertial turbulence, and at others break them. Broad-brushed parallels, therefore, obfuscate what may be biologically relevant strategies for survival and growth.
Zoom link: https://icts-res-in.zoom.us/j/87609901742?pwd=L0hjb0xMYUdEUVpQUDhFcFlIY1VqQT09
Meeting ID: 876 0990 1742
Passcode: 101022