Modeling unsteady reacting flow with operator splitting and ISAT

We examine the utility of in situ adaptive tabulation (ISAT) for the simulation of two-dimensional unsteady laminar reacting flow. The numerical scheme used to solve the low-Mach-number reacting flow equations is an operator-split projection scheme which incorporates ISAT by a Strang subsplitting procedure. The scheme is parallelized using a combination of OpenMP and MPI. ISAT is used for the pure reaction substeps, while convection and diffusion are treated explicitly by a stabilized Runge–Kutta method. We apply the scheme to a two-dimensional problem involving a laminar premixed methane–air flame interacting with a counterrotating vortex pair using detailed GRIMech3.0 chemical kinetics. Computational performance is examined; we observe an overall speed-up factor due to ISAT of approximately 2.5–3.