The moving contact line with a 180° advancing contact angle

A liquid spreading over a dry solid surface with a contact angle of 180° has always been regarded as a special case. It is commonly thought that this represents a unique situation in which a singularity does not arise in an analysis of the dynamics of the liquid when the usual hydrodynamic assumptions are made, i.e., when the liquid is Newtonian and incompressible and obeys the no-slip boundary condition at the solid. In fact, there are strong indications that it is not a special case.