Uphill motion of active brownian particles in piecewise linear potentials
Institute of Physics, Humboldt University Berlin,
Invalidenstrasse 110, 10115 Berlin, Germany
2 II. Institute of Theoretical Physics, University of Stuttgart, Pfaffenwaldring 57/III, 70550 Stuttgart, Germany
Published online: 15 March 2000
We consider Brownian particles with the ability to take up energy from the environment, to store it in an internal depot, and to convert internal energy into kinetic energy of motion. Provided a supercritical supply of energy, these particles are able to move in a "high velocity"or active mode, which allows them to move also against the gradient of an external potential. We investigate the critical energetic conditions of this self-driven motion for the case of a linear potential and a ratchet potential. In the latter case, we are able to find two different critical conversion rates for the internal energy, which describe the onset of a directed net current into the two different directions. The results of computer simulations are confirmed by analytical expressions for the critical parameters and the average velocity of the net current. Further, we investigate the influence of the asymmetry of the ratchet potential on the net current and estimate a critical value for the asymmetry in order to obtain a positive or negative net current.
PACS: 05.40.Jc – Brownian motion / 05.45.-a – Nonlinear dynamics and nonlinear dynamical systems / 05.60.-k – Transport processes
© EDP Sciences, Società Italiana di Fisica, Springer-Verlag, 2000