  Entropy-driven directed translocation of a flexible polymer through a
cone-shaped channel is studied theoretically and using computer simulation. For
a given length of the channel, the effective force of entropic origin acting on
the polymer is calculated as a function of the apex angle of the channel. It is
found that the translocation time is a non-monotonic function of the apex
angle. By increasing the apex angle from zero, the translocation time shows a
minimum and then a maximum. Also, it is found that regardless of the value of
the apex angle, the translocation time is a uniformly decreasing function of
the channel length. The results of the theory and the simulation are in good
qualitative agreement.
