Modeling subsurface reactive flows using leadership-class computing

We describe our experiences running PFLOTRAN–a code for simulation of coupled hydro-thermal-chemical processes in variably saturated, non-isothermal, porous media– on leadership-class supercomputers, including initial experiences running on the petaflop incarnation of Jaguar, the Cray XT5 at the National Center for Computational Sciences at Oak Ridge National Laboratory. PFLOTRAN utilizes fully implicit time-stepping and is built on top of the Portable, Extensible Toolkit for Scientific Computation (PETSc). We discuss some of the hurdles to "at scale" performance with PFLOTRAN and the progress we have made in overcoming them on leadership-class computer architectures.