Regensburg 2025 – scientific programme

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CPP: Fachverband Chemische Physik und Polymerphysik

CPP 2: Active Matter I (joint session DY/BP/CPP)

CPP 2.11: Talk

Monday, March 17, 2025, 12:30–12:45, H37

Self-sustained patchy turbulence in shear-thinning active fluids — •Henning Reinken and Andreas M. Menzel — Otto-von-Guericke-Universität Magdeburg

Bacterial suspensions and other active fluids are known to develop highly dynamical vortex states, denoted as active or mesoscale turbulence. We reveal the pronounced effect of non-Newtonian rheology of the carrier fluid on these turbulent states, concentrating on shear thinning. As a consequence, a self-sustained heterogeneous state of coexisting turbulent and quiescent areas develops, which results in anomalous velocity statistics. The heterogeneous state emerges in a hysteretic transition under varying activity. We provide an extensive numerical analysis and find indirect evidence for a directed percolation transition. Our results are important, for instance, when addressing active objects in biological media with complex rheological properties.

Keywords: microswimmers; mesoscale turbulence; shear thinning; directed percolation; universality