Detectable inertial effects on Brownian transport through narrow pores

We investigate the transport of suspended Brownian particles dc driven along corrugated narrow channels in a regime of finite damping. We demonstrate that inertial corrections cannot be neglected as long as the width of the channel bottlenecks is smaller than an appropriate particle diffusion length, which depends on both, the temperature and the strength of the dc drive. Therefore, transport through sufficiently narrow constrictions turns out to be sensitive to the viscosity of the suspension fluid. Applications to colloidal systems are discussed.