  We investigate the dynamics of pore-driven polymer translocation by
theoretical analysis and molecular dynamics (MD) simulations. Using the tension
propagation theory within the constant flux approximation we derive an explicit
equation of motion for the tension front. From this we derive a scaling
relation for the average translocation time $\tau$, which captures the
asymptotic result $\tau \propto N_0^{1+\nu}$, where $N_0$ is the chain length
and $\nu$ is the Flory exponent. In addition, we derive the leading
correction-to-scaling term to $\tau$ and show that all terms of order
$N_0^{2\nu}$ exactly cancel out, leaving only a finite-chain length correction
term due to the effective pore friction, which is linearly proportional to
$N_0$. We use the model to numerically include fluctuations in the initial
configuration of the polymer chain in addition to thermal noise. We show that
when the {\it cis} side fluctuations are properly accounted for, the model not
only reproduces previously known results but also considerably improves the
estimates of the monomer waiting time distribution and the time evolution of
the translocation coordinate $s(t)$, showing excellent agreement with MD
simulations.
