The work described here takes place in conjunction with an object oriented re-design of the parallel FElibrary PadFEM. The environment of PadFEM includes a graphical editor for specifying domains with boundary conditions, automatic mesh generation, automatic mesh partitioning and mapping onto the processors of a MIMD-system. The parallelization is based on PVM and MPI which guarantees portable parallel code.

We describe the PadFEM environment and OO-data structure briefly. The solver module of PadFEM includes a parallel conjugate gradient method, a parallel multigrid solver, and two different parallel preconditioned conjugate gradient methods. The preconditioning is based on domain decomposition according to Bramble and Borchers.

The FE-method works on unstructured triangular meshes which are adaptively refined using error estimates of the solution. Several different refinement strategies are implemented. To preserve load balance after refinements, a distributed load balancing algorithm based on diffusion is used. The load migration strategies try to optimize sub-domain shapes which is essential for the convergence behavior of the sub-domain solvers.

All implementations consider the concept of programming frames which allows the easy generation of user-specific code.

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