Waiwera: A parallel open-source geothermal flow simulator

Waiwera is a new reservoir simulator designed to address the current and future challenges posed by modelling geothermal systems. It incorporates several innovations aimed at improving the robustness of phase transitions and steady-state model convergence, including a modified treatment of the multi-phase gravity term. The Waiwera code is parallelised and makes extensive use of the PETSc scientific computation library. It is written in object-oriented Fortran 2003 and released under a free, open-source software license. Results from demonstration problems show a high degree of consistency with comparable simulators such as TOUGH2, improved phase transition and steady-state convergence behaviour, good parallel scalability on large problems and demonstrate the suitability of Waiwera for complex models of real geothermal reservoirs.