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MathBio Seminar

Tuesday, March 14, 2023 - 4:00pm

Jean-Luc Thiffeault

University of Wisconsin Madison


University of Pennsylvania

DRL 3C8 and via Zoom

Zoom Meeting Meeting ID: 997 9233 2298 Passcode: 657898

The active Brownian particle (ABP) model describes a microswimmer, synthetic or living, whose direction of swimming is a Brownian motion. The swimming is due to a propulsion force, and the fluctuations are often assumed thermal in origin.  We present a model where the fluctuations arise from nonthermal noise in a propelling force acting at a single point, such as that due to a flagellum.  We carefully take the overdamped limit and find several modifications to the traditional ABP model.  Since the fluctuating force causes a fluctuating torque, the diffusion tensor describing the process has a coupling between translational and rotational degrees of freedom.  An anisotropic particle also exhibits a noise-induced drift.  We show that these effects have measurable consequences for the long-time diffusivity of active particles, in particular adding a contribution that is independent of where the force acts.  This is joint work with Jiajia Guo.