Dresden 2017 – wissenschaftliches Programm
CPP 67: Focus: Topological Problems in the Physics of Polymers, Biopolymers and Fibers II (joint session BP/CPP, organized by CPP)
CPP 67.3: Vortrag
Freitag, 24. März 2017, 10:45–11:00, ZEU 222
Knotted and unknotted ring polymers under shear — •Maximilian Liebetreu and Christos N. Likos — Faculty of Physics, University of Vienna, Austria
The behavior of single 31-knotted (trefoil) rings in a fluid under shear is compared to their unknotted ring polymer counterparts. We simulate flexible polymers of a fixed size in a thermostatted Multi-Particle Collision Dynamics (MPCD) solvent (with fixed control parameters) with Lees-Edwards boundary conditions. We primarily investigate the differences in shape parameters for 31-knotted and 01-unknotted rings in dependency of shear rate, as well as characteristics of average number of beads being part of the knot (knot size), angle between knot center of mass and first principal axis relative to the polymer’s center of mass, and correlations between these quantities. We compute the relaxation time of 31-knotted rings and present results on their tumbling- and tank-treading dynamics. We obtain evidence suggesting that on a knotted ring, the 31 knot itself develops a tendency to be located near those beads closest to the orientational axis, aligned with the flow. We also show that the average knot size is decreasing with increasing shear. Preliminary findings indicate the 31-knotted rings responding to lower shear rates than their unknotted counterparts, and suggest a binary-state behavior for the 31-knotted ring under strong shear, with the knot size alternating between rather stable tight and relatively unstable delocalised configurations. Special attention is paid to the correlation between alignment angle and knot size.