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A. Zöttl, J. M. Yeomans:
"Large speed enhancement of swimming bacteria in dense polymeric fluids";
Vortrag: IUTAM Symposium on Motile Cells in Complex Environments, Udine (Italy); 15.05.2018 - 18.05.2018.

Many cells in the human body have to move through dense complex fluids such as various cells in the extracellular matrix or bacteria in
mucus. While the motion of swimming bacteria in simple Newtonian fluids can be well quantified using continuum low Reynolds num-
ber hydrodynamics, the presence of supramolecular elements such as biopolymers leads to a much more complex behavior. Although
the presence of polymers generally lowers particle mobility, surprisingly, several experiments have shown that bacterial speeds increase
in polymeric fluids [1, 2, 3, 4], but there is no clear understanding why. We perform extensive coarse-grained MPCD simulations of
a bacterium swimming in explicitly modeled solutions of supramolecular model polymers of different lengths, stiffness and densities.
We observe an increase of up to 60% in swimming speed with polymer density and show that this is a consequence of a depletion of
polymers in the vicinity of the bacterium leading to an effective slip. However, depletion alone cannot explain the large speed-up, but
coupling to the chirality of the bacterial flagellum is essential.

Projektleitung Gerhard Kahl:
DFS