  Computations of the breakup of a liquid bridge are used to establish the
limits of applicability of similarity solutions derived for different breakup
regimes. These regimes are based on particular viscous-inertial balances, that
is different limits of the Ohnesorge number $Oh$. To accurately establish the
transitions between regimes, the minimum bridge radius is resolved through four
orders of magnitude using a purpose-built multiscale finite element method.
This allows us to construct a quantitative phase diagram for the breakup
phenomenon which includes the appearance of a recently discovered low-$Oh$
viscous regime. The method used to quantify the accuracy of the similarity
solutions allows us to identify a number of previously unobserved features of
the breakup, most notably an oscillatory convergence towards the
viscous-inertial similarity solution. Finally, we discuss how the new findings
open up a number of challenges for both theoretical and experimental analysis.
