Three-dimensional field-scale coupled Thermo-Hydro-Mechanical modelling: parallel computing implementation

An approach for the simulation of three-dimensional field-scale coupled thermo-hydro-mechanical problems is presented, including the implementation of parallel computation algorithms. The approach is designed to allow three-dimensional large-scale coupled simulations to be undertaken in reduced time. Owing to progress in computer technology, existing parallel implementations have been found to be ineffective, with the time taken for communication dominating any reduction in time gained by splitting computation across processors. After analysis of the behavior of the solver and the architecture of multicore, nodal, parallel computers, modification of the parallel algorithm using a novel hybrid message passing interface/open multiprocessing (MPI/OpenMP) method was implemented and found to yield significant improvements by reducing the amount of communication required. This finding reflects recent enhancements of current high-performance computing architectures. An increase in performance of 500% over existing parallel implementations on current processors was achieved for the solver. An example problem involving the Prototype Repository experiment undertaken by the Swedish Nuclear Fuel and Waste Management Co. [Svensk Kärnbränslehantering AB (SKB)] in Äspö, Sweden, has been presented to demonstrate situations in which parallel computation is invaluable because of the complex, highly coupled nature of the problem