OpenGeoSys: Performance-Oriented Computational Methods for Numerical Modeling of Flow in Large Hydrogeological Systems

Friday, 19 December 2014
Dmitri Naumov1, Thomas Fischer1, Norbert Böttcher2, Norihiro Watanabe1, Marc Walther3, Karsten Rink1, Lars Bilke4, Haibing Shao1 and Olaf Kolditz5, (1)Helmholtz Centre for Environmental Research UFZ Leipzig, Leipzig, Germany, (2)Helmholtz-Zentrum für Umweltforschung - UFZ, Leipzig, Germany, (3)Dresden University of Technology, Dresden, Germany, (4)Helmholtz Centre for Environmental Research, Leipzig, Germany, (5)Helmholtz Center UFZ, Leipzig, Germany
OpenGeoSys (OGS) is a scientific open source code for numerical simulation of thermo-hydro-mechanical-chemical processes in porous and fractured media. Its basic concept is to provide a flexible numerical framework for solving multi-field problems for applications in geoscience and hydrology as e.g. for CO2 storage applications, geothermal power plant forecast simulation, salt water intrusion, water resources management, etc.

Advances in computational mathematics have revolutionized the variety and nature of the problems that can be addressed by environmental scientists and engineers nowadays and an intensive code development in the last years enables in the meantime the solutions of much larger numerical problems and applications. However, solving environmental processes along the water cycle at large scales, like for complete catchment or reservoirs, stays computationally still a challenging task.

Therefore, we started a new OGS code development with focus on execution speed and parallelization. In the new version, a local data structure concept improves the instruction and data cache performance by a tight bundling of data with an element-wise numerical integration loop. Dedicated analysis methods enable the investigation of memory-access patterns in the local and global assembler routines, which leads to further data structure optimization for an additional performance gain.

The concept is presented together with a technical code analysis of the recent development and a large case study including transient flow simulation in the unsaturated / saturated zone of the Thuringian Syncline, Germany. The analysis is performed on a high-resolution mesh (up to 50M elements) with embedded fault structures.