[Seminar] "Lagrangian Studies in Active and Inertial Turbulence" by Mr Rahul Kumar Singh
Mr Rahul Kumar Singh
International Centre for Theoretical Sciences, Tata Institute of Fundamental Research
Lagrangian Studies in Active and Inertial Turbulence
In this talk we discuss two very different aspects of Lagrangian turbulence in low and high Reynolds number flows. In the first half, we look at how emergent patterns in low Reynolds number active turbulent flows, for e.g. dense bacterial suspensions, result in distinct trajectories. These result in anomalous diffusion, via Lévy walks, which shows up in measurements of the mean-squared displacement and first-passage statistics. Furthermore, we uncover other aspects of Lagrangian statistics, such as dynamical heterogeneity, in such two-dimensional bacterial suspensions which underlines the key differences between active and inertial turbulence. The second half of the talk concerns the dynamics of model filaments which extend well beyond the dissipation range in high Reynolds number fluid turbulence. In particular, we show the distinctive preferential sampling of vortical structures by these filaments in both two and three dimensions. We end this talk by focussing on the gravitational settling of such chains and the complex tumbling dynamics they exhibit as they descend.
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