Meso-scale turbulence in living fluids

Wensink, Henricus H. and Dunkel, Jörn and Heidenreich, Sebastian and Drescher, Knut and Goldstein, Raymond E. and Löwen, Hartmut and Yeomans, Julia M.. (2012) Meso-scale turbulence in living fluids. Proceedings of the National Academy of Sciences of the United States of America, 109 (36). pp. 14308-14313.

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Turbulence is ubiquitous, from oceanic currents to small-scale biological and quantum systems. Self-sustained turbulent motion in microbial suspensions presents an intriguing example of collective dynamical behavior among the simplest forms of life and is important for fluid mixing and molecular transport on the microscale. The mathematical characterization of turbulence phenomena in active nonequilibrium fluids proves even more difficult than for conventional liquids or gases. It is not known which features of turbulent phases in living matter are universal or system-specific or which generalizations of the Navier-Stokes equations are able to describe them adequately. Here, we combine experiments, particle simulations, and continuum theory to identify the statistical properties of self-sustained meso-scale turbulence in active systems. To study how dimensionality and boundary conditions affect collective bacterial dynamics, we measured energy spectra and structure functions in dense Bacillus subtilis suspensions in quasi-2D and 3D geometries. Our experimental results for the bacterial flow statistics agree well with predictions from a minimal model for self-propelled rods, suggesting that at high concentrations the collective motion of the bacteria is dominated by short-range interactions. To provide a basis for future theoretical studies, we propose a minimal continuum model for incompressible bacterial flow. A detailed numerical analysis of the 2D case shows that this theory can reproduce many of the experimentally observed features of self-sustained active turbulence.
Faculties and Departments:05 Faculty of Science > Departement Biozentrum > Infection Biology > Microbiology and Biophysics (Drescher)
UniBasel Contributors:Drescher, Knut
Item Type:Article
Article Subtype:Research Article
Publisher:National Academy of Sciences
Note:Publication type according to Uni Basel Research Database: Journal article
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Last Modified:23 Jun 2021 08:22
Deposited On:23 Jun 2021 08:22

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