Polubarinova-Kochina's analytical differential equation method is used
to determine the pseudo-steady-state solution to problems involving t
he freezing (solidification) of wedges of liquid which are initially a
t their fusion temperature. In particular: we consider four distinct p
roblems for wedges which are: freezing with the same constant boundary
temperature, freezing with the same constant boundary heat fluxes, fr
eezing with distinct constant boundary temperatures and freezing with
distinct constant fluxes at the boundaries. For the last two problems,
a Heun's differential equation with an unknown singularity is derived
, which in both cases admits a particularly elegant simple solution fo
r the special case when the wedge angle is pi. The moving boundaries o
btained are shown pictorially.