In this paper a boundary problem is considered for which the boundary is to
be determined as part of the solution. A time-dependent problem involving
linear diffusion in two spatial dimensions which results in a moving free b
oundary is posed. The fundamental solution is introduced and Green's Theore
m is used to yield a non-linear system of integral equations for the unknow
n solution and the location of the boundary. The boundary element method is
used to obtain a numerical solution to this system of integral equations w
hich in turn is used to obtain the solution of the original problem. Graphi
cal results for a two-dimensional problem are presented. Published in 1999
by John Wiley & Sons, Ltd.