Regensburg 2019 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 26: Active matter I (joint session BP/CPP/DY)
DY 26.8: Vortrag
Mittwoch, 3. April 2019, 11:45–12:00, H4
Enhanced rotational diffusion of squirmers in viscoelastic fluids — •Kai Qi1, Elmar Westphal2, Gerhard Gompper1, and Roland Winkler1 — 1Theoretical Soft Matter and Biophysics, Institute for Advanced Simulation and Institute of Complex Systems, Forschungszentrum Jülich, D-52425 Jülich, Germany — 2Peter Grünberg Institute and Jülich Centre for Neutron Science, Forschungszentrum Jülich, D-52425 Jülich, Germany
Squirmers are generic models for biological microswimmers and synthetic self-propelled particles. Fluid-mediated interactions are essential for their swimming behavior, which can be strongly affected by the fluid viscoelasticity. Here, we perform mesoscale hydrodynamic simulations via the multiparticle collision dynamics (MPC) method for a spherical squirmer in a viscoelastic fluid, which is composed of MPC fluid particles and polymers. Polymers are either of phantom nature or self-avoiding. The concentration of monomers on the squirmer surface is enhanced by introducing a short-range attraction between the squirmer and polymers. This leads to a decrease of the rotational diffusion for a passive colloid in the presence of polymers. Self-propulsion reduces the monomer concentration on the surface and the squirmer’s rotational diffusion is enhanced considerably, up to a factor 20 for phantom polymers. The actual change of the rotational diffusion Dr depends on the polymer length. An increasing polymer length reduces Dr0 of the passive colloid, but Dr of the squirmer is enhanced. Both effects contribute to the obtained substantial increase of the ratio Dr/Dr0.