A task-based parallel framework for ensemble simulations of rocket ignition *

We present an integrated, parallel computational framework for exascale-oriented ensemble simulations of laser-induced ignition in a methane-oxygen rocket combustor. The framework employs the reacting flow solver HTR (Di Renzo et al., Comp. Phys. Comm. 2020). The solver uses the task-based programming model built on the Legion runtime system to achieve scalable simulation on supercomputers with heterogeneous architectures. The compressible, multi-species Navier-Stokes equations with finite-rate combustion chemistry are discretized on curvilinear grids using a low-dissipation conservative formulation. Laser-induced ignition is modeled by rapid, intense energy-deposition. This solver is integrated in a continuous development environment to manage a large software development team. The framework also leverages Legion’s mapper to efficiently perform the execution of ensembles simultaneously on GPUs and CPUs across multiple fidelities to carry out reliability and uncertainty quantification studies. We show verification examples as well as demonstrate the framework through combustor simulations using representative parameters.