Numerical modeling of 3D thermomechanical problems is a complex and time consuming issue. Adaptive techniques are powerful tools to perform efficiently such modeling using the FEM analysis. During adaptation computational workloads change unpredictably at the runtime, therefore dynamic load balancing is required.

This paper presents the parallel adaptive FEM package NuscaS with the dynamic load balancing for 3D unstructured meshes. This 
object-oriented package for the parallel FEM modeling is developed at Czestochowa University of Technology to investigate different thermomechanical phenomena. NuscaS uses the message-passing paradigm, and is suitable for distributed memory parallel computers
such as PC-clusters. The implementation of adaptation in NuscaS is based on using the ParMETIS tool for the mesh repartitioning and load balancing. 

Multigrid methods are among the fastest numerical algorithms for solving large sparse systems of linear equations. Multigrid is also a good preconditioning algorithm for Krylov iterative solvers. That is why, in this paper we present also parallelisation aspects of geometric multigrid algorithms developed for the NuscaS package.
A parallel conjugate gradient method with multigrid preconditioning is used for solving FEM problems using NuscaS on PC-clusters.