DTLreactingFoam: An efficient CFD tool for laminar reacting flow simulations using detailed chemistry and transport with time-correlated thermophysical properties

Abstract

The official OpenFOAM distributions are currently not well-suited for accurate simulations of laminar reacting flows, primarily due to the restrictive Sutherland transport model and the oversimplified unity Lewis number assumption. These limitations can be addressed by employing a detailed transport model (DTM) grounded in kinetic gas theory. However, this approach significantly increases computational cost. To resolve this trade-off, we present a newly developed framework, DTLreactingFoam, designed for simulating laminar flames with integrated detailed transport and chemical kinetics while maintaining computational efficiency. The first level of cost reduction is achieved by incorporating a polynomial-fit transport model (FTM). Further acceleration is provided by a time-correlated thermophysical property evaluation (coTHERM) method, which dynamically updates properties at each time step or iteration by exploiting their temporal correlations. The framework is validated through a series of canonical laminar flame simulations. The results show excellent agreement with experimental measurements and benchmark software, confirming the accurate implementation of both the DTM and FTM. Moreover, validation results demonstrate that coupling the coTHERM method with either the DTM or FTM enables high-fidelity laminar flame simulations with substantially reduced computational cost. Notably, using the coTHERM method in conjunction with the FTM achieves up to a 77% reduction in computational time compared to the direct use of the DTM, without compromising accuracy.

PROGRAM SUMMARY Program Title: DTLreactingFoam CPC Library link to program files: (to be added by Technical Editor) Developer’s repository link (OF-12): https://github.com/danhnam11/DTLreactingFoam-12 Developer’s repository link (OF-10): https://github.com/danhnam11/DTLreactingFoam-10 Developer’s repository link (OF-8): https://github.com/danhnam11/DTLreactingFoam-8 Code Ocean capsule: (to be added by Technical Editor) Licensing provisions: GPLv3 Programming language: C++ Supplementary material: Nature of problem: Using the detailed transport model (DTM) based on the principles of kinetic gas theory can accurately simulate laminar reacting flows in OpenFOAM (OF). However, the accuracy comes at the cost of significantly greater computational effort since all thermophyscal properties are recomputed in every single cell and at every time step throughout the simulation when using DTM in OF. Solution method: In reacting flow simulations, the evolution of thermodynamic state variables and species concentrations between successive steps are correlated. The change in these quantities from one step to the next are often minimal since the time steps used in combustion simulations are typically small (i.e., on the microsecond scale or smaller). Therefore, if these variations are sufficiently small, it is unnecessary to recompute thermophysical properties at every time step, and they can instead be reasonably treated as time-invariant over short intervals. This technique is referred to as time-correlated thermophysical property evaluation (coTHERM). It can reduce a huge computational cost for numerical simulations using DTM in OF while preserving the accuracy.

References: All appropriate methodological references are included in the section entitled References.