Berlin 2012 – wissenschaftliches Programm

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DY: Fachverband Dynamik und Statistische Physik

DY 25: Brownian Motion and Transport

DY 25.5: Vortrag

Donnerstag, 29. März 2012, 10:45–11:00, MA 004

Non-equilibrium effects on granular Brownian motors — •Johannes Blaschke and Jürgen Vollmer — Max Planck Institute for Dynamics and Self Organization, Göttingen, Germany

It has been shown that an appropriately-shaped object, immersed in a Maxwellian gas and restricted to move only in one direction, released from rest will settle away from its point of release as it equilibrates with the gas.

When making the collisions between gas particles and motor inelastic, the device surprisingly acquires a finite steady state velocity. While this has been called a ``Granular Brownian Motor'', realistic granular gasses have finite particle-particle restitution coefficients leading to constant dissipation within the gas. As a consequence energy needs to be injected into the gas to keep it from freezing. This results in a system which is inherently not in equilibrium. Furthermore, energy generally cannot be injected homogeneously and instead is frequently injected at the walls, manifesting in a non-isotropic particle velocity distribution. This ultimately results in a particle velocity distribution that is both non-Maxwellian and appears as squeezed.

We have examined the motion of a Brownian motor in gases with realistic non-Maxwellian and squeezed particle velocity distribution.