The purpose of this paper is to address the following problem: How can

existing sequential simulators be utilized in developing parallel simulators

for the numerical solution of partial dierential equations (PDEs)? We dis-

cuss this issue in the light of object-oriented (OO) programming techniques,

which can substantially increase the eciency of implementing parallel PDE

software. Our parallelization approach is to use domain decomposition (DD)

as an overall numerical strategy.