SKM 2023 – wissenschaftliches Programm
DY 33.2: Vortrag
Mittwoch, 29. März 2023, 15:15–15:30, ZEU 250
Non-monotonic behavior of timescales of passage in heterogeneous media: Dependence on the nature of barriers — Moumita Dasgupta1, •Sougata Guha2, Leon Armbruster1, Dibyendu Das2, and Mithun K. Mitra2 — 1Department of Physics, Augsburg University, USA — 2Department of Physics, IIT Bombay, India
Usually time of passage across a region may be expected to increase with the number of barriers along the path. Can this intuition fail depending on the special nature of the barrier? We study experimentally the transport of a robotic bug which navigates through a spatially patterned array of obstacles. Depending on the nature of the obstacles we call them either entropic or energetic barriers. For energetic barriers we find that the timescales of first passage vary non-monotonically with the number of barriers, while for entropic barriers first passage times increase monotonically. We perform an exact analytic calculation to derive closed form solutions for the mean first passage time for different theoretical models of diffusion. Our analytic results capture this counter-intuitive non-monotonic behaviour for energetic barriers. We also show non-monotonic effective diffusivity in the case of energetic barriers. Finally, using numerical simulations, we show this non-monotonic behaviour for energetic barriers continues to hold true for super-diffusive transport. These results may be relevant for timescales of intra-cellular biological processes.