# C7 (N): Dense active suspensions in the chaotic regime

The goal of the project is to investigate active particle motion in a soluble medium (bacteria or active colloids) in the chaotic flow regime (“turbulence”) on an essentially two-dimensional manifold. We employ three differ-ent methods bridging the scales from microscopic particle motion to the continuum. On the smallest scale, we conduct (i) direct numerical simulations. This will be the basis for the construction of a (ii) mixture model founded on the Eulerian spatial averaging leading to an effective flow model. Built on this, a (iii) probability density function description and, in turn, its group theoretical properties will be the final goal to understand the complete and detailed statistics of the problem.

Funding for this project has started in July 2018.

Probability theory of active suspensions

Physics of Fluids 33 (6),
061902
(2021);

doi:10.1063/5.0047227

Vorticity Determines the Force on Bodies Immersed in Active Fluids

Physical Review Letters 126 (13),
(2021);

doi:10.1103/physrevlett.126.138002

High-order simulation scheme for active particles driven by stress boundary conditions

Journal of Physics: Condensed Matter 33 (24),
244004
(2021);

doi:10.1088/1361-648x/abf8cf

Quorum-sensing active particles with discontinuous motility

Physical Review E 101 (1),
012601
(2020);

doi:10.1103/physreve.101.012601

From scalar to polar active matter: Connecting simulations with mean-field theory

Physical Review E 101 (2),
(2020);

doi:10.1103/physreve.101.022602

Statistical theory of helical turbulence

Physics of Fluids 32 (6),
065109
(2020);

doi:10.1063/5.0010874

## Contact

- Prof. Dr.-Ing. Martin Oberlack
- Department of Mechanical Engineering
- Technische Universität Darmstadt
- Otto-Berndt-Str. 2
- D-64287 Darmstadt
- Tel: 49 6151 16-26200
- officeQDjca..jc@okEfdy.tu-darmstadt.de
- https://www.fdy.tu-darmstadt.de/fdy/fdystaff/details_16448.de.jsp

- Prof. Dr. Thomas Speck
- Institut für Physik
- Universität Mainz
- Staudingerweg 9
- D-55128 Mainz
- Tel: +49 6131 39 26915
- Fax: +49 6131 39 20496
- thomas.speckUZpAf@dzDhuRuni-mainz.de
- https://www.komet1.physik.uni-mainz.de/people/thomas-speck

- Prof. Dr. Yongqi Wang
- Department of Mechanical Engineering
- Technische Universität Darmstadt
- Otto-Berndt-Str. 2
- D-64287 Darmstadt
- Tel: +49 6151 16-26202
- Fax: +49 6151 16-26203
- wangRjgeGrGBv@xv_fzfdy.tu-darmstadt.de
- https://www.fdy.tu-darmstadt.de/fdy/fdystaff/details_17472.de.jsp