Dresden 2020 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 67: Active Matter V (joint session DY/BP/CPP)

DY 67.2: Talk

Friday, March 20, 2020, 10:15–10:30, ZEU 160

The role of inertia in active nematic turbulence — •Colin-Marius Koch and Michael Wilczek — Max Planck Institute for Dynamics and Self-Organization, Göttingen, Germany

Suspensions of active agents with nematic interactions can exhibit complex spatio-temporal dynamics such as mesoscale turbulence. Continuum descriptions for such systems are inspired by the hydrodynamic theory of liquid crystals and introduce additional effects of active stresses. The resulting equations feature an advective nonlinearity which represents inertial effects. The typically low Reynolds number of such active flows raises the question of the importance of the inertial effects. To address this question, we numerically investigate turbulent flows in a two-dimensional dense suspension of active nematic liquid crystals. We qualitatively compare numerical simulations with and without nonlinear advection of the flow field. We find that for sufficiently high activity, the simulations considering the advection term display large-scale motion not observed when excluding inertia. Performing a spectral analysis of the energy budget, we identify an inverse energy transfer to the largest scales highlighting the importance of inertial effects in this model. We additionally show that surface friction, mimicked by a linear friction term, dissipates the transported energy and slows down the large-scale motion.