Run-Reverse-Flap Active Motility

Run-Reverse-Flap (RRF) motility is used by many bacteria and C. elegans: run forward at speed v, then either reverse (flip 180°) or flap (turn by angle φ ≈ 90°). This creates persistent random walks with D_eff = v²/(2λ(1−cos φ)) — far exceeding thermal diffusion. The mean square displacement (shown in the right panel) deviates from Brownian (dashed) at short times due to persistence, then crosses over to enhanced diffusion.