There has been progress on the mathematical side, which, though smaller
in scale, is also significant. Apart from an unfortunate aberration period,
during which it became fashionable to prove that the two-phase equations
were insoluble, applied mathematicians (or, more often, engineers taking
over their role) have made steady advances. They have modestly improved
solution algorithms, clarified the relative merits of implicit and explicit
formulations, for the most part **ignored the siren voices from the "finite
element" champ**, and learned to accept and work within the limitations
that they could not transcend.