In the present chapter, the principles of the boundary element methods for
phase change problems over domains with fixed boundaries are developed briefly.
The details are developed starting from the 1-D diffusion problems over domains
with fixed boundaries subjected to different types of boundary and initial conditions.
In these problems, a new criterion has emerged: the existence of a moving
boundary, which requires special treatment when solving overall problems.
Keywords: Boundary elements methods, phase change problems, moving boundary problems, Stefan condition.