Ratchet, pawl and spring Brownian motor

TL;DR

This paper models a thermal Brownian motor inspired by Feynman's ratchet and pawl, where the components are in different thermal baths connected by a spring, analyzing its dynamics through simulations and analytical approximations.

Contribution

It introduces a novel model of a Brownian motor with components in separate thermal baths connected by a spring, providing both numerical and analytical insights.

Findings

Analytical expression for mean velocity under external torque and temperature differences

Numerical simulations confirm the analytical predictions within approximation limits

The model demonstrates how thermal gradients drive directed motion in microscopic systems

Abstract

We present a model for a thermal Brownian motor based on Feynman's famous ratchet and pawl device. Its main feature is that the ratchet and the pawl are in different thermal baths and connected by an harmonic spring. We simulate its dynamics, explore its main features and also derive an approximate analytical solution for the mean velocity as a function of the external torque applied and the temperatures of the baths. Such theoretical predictions and the results from numerical simulations agree within the ranges of the approximations performed.