Investigation On The Directed Transport Of Feedback-coupled Brownian Ratchets

Brownian ratchets are nonequilibrium systems which rectify thermal fluctuations toachieve directed motion, using temporal or spatial asymmetry, and its mechanism is notonly very important for the deep investigation of life sciences, but also one of hot topicsof biology, physics, nanotechnology and so on.In this work, it is investigated that the directed transport performance of twofeedback-coupled Brownian particles without external force or with the external force inthe single-well ratchet potential and the double-well ratchet potential via solvingLangevin equation numerically. The background and the significance of Brownianratchets are given. Moreover, the evolutive histories, the classification, the structure andthe functions of the molecular motors are given. The dynamics theory, Langevin equationand flashing ratchet are given with the noise in detail. The average velocity of Brownianparticles, the average effective diffusion efficientD effand Pe number are calculated,and the influences of the length of the spring, the intensity of noise, the external force, theasymmetric parameter of the double-well ratchet potential, the coupling constant andother parameters of model on the directed transport performance of feedback-coupledparticles are analyzed. The results of different well potential are compared.The results demonstrate that the average velocity of coupled Brownian particles islarger in the double-well ratchet potential than that in the single-well ratchet potentialwithout external force, which means the directed transport of coupled particles may beenhanced in the double-well ratchet potential. The average velocity of Brownian particleschanges periodically under the external force. Furthermore, there exists an optimal valueof the asymmetric parameter of the double-well ratchet potential at which the currentreaches the maximum. The average effective diffusion efficientD effincreases as theintensity of the noise increases in the presence of periodic driving force, which indicatesthat the higher the temperature, the easier the diffusion of particles is.