Fluctuational Features of Diffusive Passage of Particles in Narrow Channels with Obstacles

The dynamics of test particles experiencing shifted diffusion under the effect of an external constant force are studied in channels of variable a cross section with impenetrable walls. It is shown that, depending on the ratio of the width of the channel in its narrowest part to the characteristic size of the inlet part of the channel and on the place where the particle enters the narrowing channel, different fluctuation modes arise when the particle passes through a narrow channel of variable cross section, which differ in the scaling exponents of fluctuations.