exploring the dynamics of active matter from a single chiral active brownian particle to collective thermophoresis of active rods

Abstract

Active matter has emerged as a fascinating field of research over the last few decades. Active newlinematter is driven out of equilibrium on the shortest scale of individual constituents, consuming newlineand dissipating energy from the local environment or internal energy source. It can self-propel newlineby conversion of energy into mechanical motion, breaking the time-reversal symmetry and newlineequilibrium fluctuation-dissipation relation. Active matter can be found in the natural world newlinein a variety of levels ranging from the single particle level (molecular motors, individual cells, newlineand bacteria) to the collective level (bird flocks, fish schools, or human crowds). Taking inspi- newlineration from such natural active matter systems, researchers have also designed artificial active newlinematter systems in the laboratory environment, e.g., Janus particles (using phoretic force as newlinethe source of self-propulsion), vibrated granular matter, and hexbugs. In this thesis, we have newlineexplored both the single-particle dynamics and the collective behavior of active-matter sys- newlinetems. First, we investigate the dynamics of a single chiral active Brownian particle to capture newlinethe essence of the active matter dynamics at the single particle level. Next, we studied the newlinecollective thermophoresis of self-propelled active rods in the presence of a temperature gradient. newlineThe motion of self-propelled agents is often described in terms of three related models: the ac- newlinetive Brownian particles (ABP), run-and-tumble particles (RTP), and active Ornstein-Uhlenbeck newlineprocess (AOUP). Up to the second moment, their dynamics is equivalent and can easily be newlinemapped from one to another. The generation of self-propulsion often utilizes a break in parity newlinein the direction of motion, the heading direction, which undergoes either continuous (ABP, newlineactive colloids) or discrete reorientation (RTP, bacteria). In the active phoretic motion of newlinecolloids, such asymmetry is inherent to the design of Janus colloids. However, the left-right newlineparity symmetry around the heading direction can also be broken f