Computationally efficient implementation of combustion chemistry using<b>in situ</b>adaptive tabulation

TLDR

In PDF methods, the ISAT technique enables the use of detailed kinetic mechanisms for turbulent combustion calculations. The authors present a computational technique that reduces the time required to treat detailed chemistry in reactive flow calculations by three orders of magnitude. The method uses in situ adaptive tabulation of the accessed composition space to control errors, and is tested on non‑premixed methane‑air combustion in a turbulent reactor with a 16‑species, 41‑reaction mechanism, while also being applicable to reduced mechanisms and other reactive‑flow approaches. The approach achieves excellent error control within the specified tolerance and delivers a speed‑up of about 1000× compared to direct numerical integration of the reaction equations.

Abstract

A computational technique is described and demonstrated that can decrease by three orders of magnitude the computer time required to treat detailed chemistry in reactive flow calculations. The method is based on the in situ adaptive tabulation (ISAT) of the accessed region of the composition space - the adaptation being to control the tabulation errors. Test calculations are performed for non-premixed methane - air combustion in a statistically-homogeneous turbulent reactor, using a kinetic mechanism with 16 species and 41 reactions. The results show excellent control of the tabulation errors with respect to a specified error tolerance; and a speed-up factor of about 1000 is obtained compared to the direct approach of numerically integrating the reaction equations. In the context of PDF methods, the ISAT technique makes feasible the use of detailed kinetic mechanisms in calculations of turbulent combustion. The technique can also be used with reduced mechanisms, and in other approaches for calculating reactive flows (e.g. finite difference methods).