BPCPPDYSOE21 – wissenschaftliches Programm
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DY: Fachverband Dynamik und Statistische Physik
DY 24: Dynamics and Statistical Physics - Open Session
DY 24.4: Vortrag
Dienstag, 23. März 2021, 12:00–12:20, DYb
Unravel the rotational properties of a squirmer in viscoelastic fluids — •Kai Qi1, Marco De Corato2, and Ignacio Pagonabarraga1 — 1CECAM, EPFL, Lausanne, Switzerland — 2IBEC, BIST, Barcelona, Spain
We investigate the rotational motion of a single swimmer in viscoelastic fluids via Lattice Boltzmann (LB) simulations. Here, the generic squirmer model is employed and fluid viscoelasticity is achieved by added flexible polymer chains. The interplay of activity and boundary conditions between the squirmer and polymers on the squirmer's rotational motion is addressed. For Reynolds number close to unity, the rotational diffusion of a pusher/puller that employs the no-split boundary condition is enhanced over an order of magnitude. This is mainly due to the asymmetric torques generated during the heterogeneous collisions between the squirmer and polymers. However, this enhancement is about 5 times weaker when a short-range repulsion between squirmer's surface and monomers is used. By increasing system viscosity, we decrease the Reynolds number by an order of magnitude. Consequently, polymer's motility is suppressed profoundly. We find that the rotational diffusion coefficients of a pusher/neutral swimmer obtained from two boundary conditions are nearly identical. But the rotational enhancement of a puller with a no-slip boundary condition is twice stronger compared with the one exploiting short-range repulsion. This is because collisions occur mainly in the front of a puller due to its special swimming scheme.