Nonlinear dynamics and bifurcations of an active Janus particle undergoing frequency-dependent electrophoretic motion in a quiescent fluid under gravity Article

Vaknin, Y, Boymelgreen, A, Gottlieb, O et al. (2027). Nonlinear dynamics and bifurcations of an active Janus particle undergoing frequency-dependent electrophoretic motion in a quiescent fluid under gravity . PHYSICA D-NONLINEAR PHENOMENA, 499 10.1016/j.physd.2026.135455

cited authors

  • Vaknin, Y; Boymelgreen, A; Gottlieb, O; Miloh, T

authors

abstract

  • This study explores the nonlinear dynamics and the bifurcation structure of an active spherical Janus particle (JP) subjected to combined gravitational and AC electrophoretic forces within an unbounded electrolyte. We extend the existing ‘weak-field’ dipolophoretic (DIP) models under a thin Debye layer, to include the effect of gravity and also introduce the concept of a frequency-dependent correction factor to adjust for the contribution of the induced-charge electrophoretic (ICEP) torque. Using a genetic algorithm, we develop an optimized model for this adjustment factor and validate it against experimental benchmarks. The model facilitates examination of the critical role of a JP gravitational tilt angle on the bifurcation structure and transient dynamics of a metallodielectric nano/micro sphere. The analysis reveals the existence of three distinct bifurcation regions that are governed by the density ratio between the two JP hemispheres, including two regions of unique stable equilibria which are separated by two supercritical pitchfork bifurcations that confine a region with bistable equilibria. These new insights advance our understanding of active Janus particle nonlinear fluid-structure interaction under realistic gravity conditions, providing implications for applications in microfluidics, targeted drug delivery, and active matter systems.

publication date

  • January 1, 2027

published in

Digital Object Identifier (DOI)

volume

  • 499