Regensburg 2007 – scientific programme

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DY: Fachverband Dynamik und Statistische Physik

DY 24: Poster I

DY 24.43: Poster

Wednesday, March 28, 2007, 16:00–18:00, Poster D

Persistent and directed random walks with speed and angular fluctuations in two dimensions — Fernando Peruani^1,2 and •Luis Guillermo Morelli¹ — ¹Max Planck for the Physics of Complex Systems, Dresden, Germany — ²Technische Universitaet Dresden, Dresden, Germany

We study the motion of self-propelled particles with fluctuations in the speed and the direction of motion, in two dimensions. We consider the case in which fluctuations in the speed are not correlated to fluctuations in the direction of motion, and assume that both processes can be described by independent characteristic times. We investigate the dynamics of persistent and directed random walks, and derive exact expressions for the mean displacement and the mean squared displacement for arbitrary speed and angular stationary distributions. We show that both persistent and directed random motion with speed fluctuations exhibit a series of alternating ballistic and diffusive regimes, which arise from the interplay between the different time-scales involved. Our results could be relevant to estimate motility indexes from experiments involving living cells or other self-propelled particles.