Dynamics of a deformable active particle under shear flow

Abstract

The motion of a deformable active particle in linear shear flow is explored theoretically. Based on symmetry considerations, in two spatial dimensions, we propose coupled nonlinear dynamical equations for the particle position, velocity, deformation, and rotation. In our model, both, passive rotations induced by the shear flow as well as active spinning motions, are taken into account. Our equations reduce to known models in the two limits of vanishing shear flow and vanishing particle deformability. For varied shear rate and particle propulsion speed, we solve the equations numerically and obtain a manifold of different dynamical modes including active straight motion, periodic motions, motions on undulated cycloids, winding motions, as well as quasi-periodic and chaotic motions induced at high shear rates. The types of motion are distinguished by different characteristics in the real-space trajectories and in the dynamical behavior of the particle orientation and its deformation. Our predictions can be verified in experiments on self-propelled droplets exposed to a linear shear flow.

Helical paths, gravitaxis, and separation phenomena for mass-anisotropic self-propelling colloids: Experiment versus theory

“…53,54 With regard to the motion of microorganisms in nature, it would be an interesting task for the future to extend our work towards mass-anisotropic self-propelled colloidal particles in shear flow, [55][56][57] where we expect even more complex trajectories. Table II.…”

Emergent behavior in active colloids

“…This becomes even more complicated in the presence of bounding surfaces [210,[224][225][226], where active colloids can swim stably against the flow and show rheotaxis [224,226]. Finally, deformable active particles such as active droplets in flow also show complex swimming trajectories [227].…”

Getting drowned in a swirl: Deformable bead-spring model microswimmers in external flow fields

“…The study of this particular flow field offers two major advantages. On the one hand, and in contrast to the often analyzed linear shear profile [13,98], a swirl flow can easily be realized experimentally. In the simplest case, a swirl can be induced in a cylindrical cavity of sufficient diameter and height by a rotating magnetic stir bar at the bottom of the vessel.…”

“…[1][2][3][4][5][6] for recent reviews. This includes the individual dynamics of particles with complex shape [7][8][9], as well as cases of self-rotation [9][10][11][12][13][14][15]. Furthermore, the collective behavior of many such interacting particles has been explored [16][17][18][19][20][21][22][23][24][25][26][27][28][29][30][31][32][33][34][35].…”