Direct Numerical Simulation of Non-premixed Syngas Combustion Using OpenFOAM

A direct numerical simulation (DNS) solver for turbulent reacting flows is developed using libraries and functions from the open-source computational fluid dynamics package OpenFOAM. The solver serves as a reference for developing sub-grid scale models for the large eddy simulation (LES) of turbulent flames. DNS typically requires spatial and temporal discretisation schemes of high order, which are not readily available in OpenFOAM. We validate our OpenFOAM solver by performing direct numerical simulations of a well-defined DNS case featuring non-premixed syngas combustion in a double shear layer. This configuration has previously been studied by Hawkes et al. (Proc Combust Inst 31:1633–1640, 2007) using a purpose-built, high-order DNS solver. Despite the lower discretisation schemes of OpenFOAM, simulation results agree very well with the reference DNS data. Local extinction and re-ignition of the syngas flame are captured and effects of differential diffusion are highlighted. Parallel scaling results using the HazelHen architecture of HLRS Stuttgart are reported.