OpenFOAM is one of the most widely used open-source computational fluid dynamics tools and often employed for chemical engineering applications. However, there is no systematic assessment of OpenFOAM’s numerical accuracy and parallel performance for chemically reacting flows. For the first time, this work provides a direct comparison between OpenFOAM’s built-in flow solvers as well as its reacting flow extension EBIdnsFoam with four other, well established high-fidelity combustion codes. Quantification of OpenFOAM’s numerical accuracy is achieved with a benchmark suite that has recently been established by Abdelsamie et al. (Comput Fluids 223:104935, 2021. https://doi.org/10.1016/j.compfluid.2021.104935) for combustion codes. Fourth-order convergence can be achieved with OpenFOAM’s own cubic interpolation scheme and excellent agreement with other high-fidelity codes is presented for incompressible flows as well as more complex cases including heat conduction and molecular diffusion in multi-component mixtures. In terms of computational performance, the simulation of incompressible non-reacting flows with OpenFOAM is slower than the other codes, but similar performance is achieved for reacting flows with excellent parallel scalability. For the benchmark case of hydrogen flames interacting with a Taylor–Green vortex, differences between low-Mach and compressible solvers are identified which highlight the need for more investigations into reliable benchmarks for reacting flow solvers. The results from this work provide the first contribution of a fully implicit compressible combustion solver to the benchmark suite and are thus valuable to the combustion community. The OpenFOAM cases are publicly available and serve as guide for achieving the highest numerical accuracy as well as a basis for future developments.

The objective of the current paper is to clarify the physical distinction between turbulence modulations by laden particles in decaying isotropic turbulence and stationary isotropic turbulence. Direct numerical simulations of stationary and decaying isotropic turbulence were carried out using 128³ grid points at a Taylor micro-scale Reynolds number of R_λ ∼ 70. The effect of O(10⁶) solid particles with a different Stokes number (St) was implemented as a point-force approximation in the Navier-Stokes equation. Turbulent kinetic energy, acceleration, enstrophy, strain rate, and various spectra were examined to determine the distinctions. Turbulence modulation in decaying turbulence is qualitatively and quantitatively inconsistent compared to that in stationary turbulence, particularly when the particles have St ≤ 1, mainly due to the artificial forcing necessary for stationary status. For the particles with St > 1, however, decaying and stationary turbulence are qualitatively similar. A simple analysis confirms that stationary turbulence is not appropriate for the study of turbulence modulation by particles with St ≤ 1. Furthermore, the injection perturbation of particles has a significant effect on turbulence modulation in decaying turbulence. An investigation of the correlation between turbulence field zones and the two-way interaction energy was conducted to gain a better understanding of the modulation mechanism.

A hybrid solver for low-Mach combustion simulations has been proposed and validated through different test-cases in a previous publication [Hosseini et al., “Hybrid lattice Boltzmann-finite difference model for low Mach number combustion simulation,” Combust. Flame 209, 394–404 (2019)]. However, all the considered configurations were laminar, far from realistic applications. To check the performance of this approach for more complex physical processes, the developed solver is used here to model a variety of transitional and turbulent reacting flows. It is first used to compute an established benchmark, the Taylor–Green vortex, for (a) an iso-thermal single-component fluid, (b) a thermal non-reacting mixture, and (c) a thermal reacting mixture (hydrogen/air flame). Detailed comparisons of the results against a high-order in-house direct numerical simulation solver show that the proposed hybrid lattice Boltzmann solver correctly captures the dynamics of the flow at relatively low numerical cost. This same solver is then used to model the interaction of a methane/air flame with a vortex pair, revealing different interaction regimes of interest for turbulent combustion models. It is further employed to model the interaction of an expanding circular flame kernel with a pair of vortices and correctly captures the characteristic regimes. To showcase its ability to deal with turbulent flows, it is finally applied to a homogeneous isotropic turbulent configuration.