# A minimally-dissipative low-Mach number solver for complex reacting flows in OpenFOAM

## TL;DR

This paper introduces an open-source LES solver for low-Mach number turbulent combustion in OpenFOAM, emphasizing minimal kinetic energy dissipation for improved accuracy in complex geometries.

## Contribution

It develops a minimally-dissipative, collocated-mesh LES solver tailored for unstructured grids in OpenFOAM, enhancing simulation fidelity for complex reacting flows.

## Key findings

- Validated on manufactured solutions for accuracy.
- Demonstrated on canonical and turbulent sooting flame cases.
- Achieved minimal kinetic energy dissipation in simulations.

## Abstract

Large eddy simulation (LES) has become the de-facto computational tool for modeling complex reacting flows, especially in gas turbine applications. However, readily usable general-purpose LES codes for complex geometries are typically academic or proprietary/commercial in nature. The objective of this work is to develop and disseminate an open source LES tool for low-Mach number turbulent combustion using the OpenFOAM framework. In particular, a collocated-mesh approach suited for unstructured grid formulation is provided. Unlike other fluid dynamics models, LES accuracy is intricately linked to so-called primary and secondary conservation properties of the numerical discretization schemes. This implies that although the solver only evolves equations for mass, momentum, and energy, the implied discrete equation for kinetic energy (square of velocity) should be minimally-dissipative. Here, a specific spatial and temporal discretization is imposed such that this kinetic energy dissipation is minimized. The method is demonstrated using manufactured solutions approach on regular and skewed meshes, a canonical flow problem, and a turbulent sooting flame in a complex domain relevant to gas turbines applications.