Progress Towards Direct Numerical Simulations of Plumes and Pool Fires

Computational simulations of fire have the potential to provide new physical understanding of fire dynamics and evolution in both natural and built environments. However, such simulations are challenging due to the multi-physics, multi-scale nature of essentially all fires. In this talk, we present new results from a computational effort focused on understanding and characterizing wildland fire spread at small scales (roughly 1m–1mm) using direct numerical simulations (DNS). The cost of the simulations is reduced using adaptive mesh refinement (AMR), where resolution is provided only when and where it is needed to resolve physically-relevant fine-scale features. Simulation results are shown for both large-scale plumes and pool fires studied experimentally in the FLAME facility at Sandia National Lab. In the plume configuration, helium gas is released into ambient air from a 1m inlet. In the pool fire configuration, methane is released into ambient air from the same 1m inlet, before burning as a non-premixed diffusion flame. Comparisons are made between results from the simulations with and without AMR, and between the simulations and experiments. Focus is placed, in particular, on the computational savings enabled by the use of AMR, in addition to simulation accuracy.