A Systematic Assessment of Artificial Flame Thickening for Thermodiffusively Unstable Lean Hydrogen Flames in Homogeneous Isotropic Turbulence
Abstract
The Artificially Thickened Flame (ATF) approach is widely used to render premixed flames resolvable on coarse computational meshes, but thickening alters their interaction with turbulence. While considerable research has focused on the effects of thickening on turbulence-induced flame wrinkling, its influence on the mean local flame propagation speed in turbulent, thermodiffusively unstable hydrogen flames remains poorly understood. More than 200 flame-resolved simulations of premixed flames in homogeneous isotropic turbulence with detailed chemistry and transport are used to systematically isolate and quantify the effects of artificial thickening. Thickening the flame by a factor F increases its effective flame-scale Karlovitz number according to KafF = Kaf√F, while decreasing its effective Damköhler number according to DafF = Daf/F. In the regime considered here, the former enhances the mean local flame speed, whereas the latter reduces flame wrinkling, resulting in opposing effects on the flame consumption speed; hence, changes in both local flame propagation and flame area must be accounted for. Simulations matched with respect to KafF and DafF collapse across different thickening factors F until the thickened flame approaches the integral or geometric length scales of the configuration. Based on these scaling relations, a self-consistent efficiency correction is proposed to recover the unthickened flame consumption speed. Since the efficiency factor feeds back on the effective Karlovitz and Damköhler numbers, it must be determined implicitly.
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BibTeX
@misc{schneider2026systematic,
title = {{A Systematic Assessment of Artificial Flame Thickening for Thermodiffusively Unstable Lean Hydrogen Flames in Homogeneous Isotropic Turbulence}},
author = {Max Schneider and Vinzenz Schuh and Felix Rong and Driss Kaddar and Andrew J. Aspden and Thomas L. Howarth and Christian Hasse and Hendrik Nicolai},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.37577},
eprint = {2610.37577},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.37577},
}
RIS
TY - UNPB
TI - A Systematic Assessment of Artificial Flame Thickening for Thermodiffusively Unstable Lean Hydrogen Flames in Homogeneous Isotropic Turbulence
AU - Max Schneider
AU - Vinzenz Schuh
AU - Felix Rong
AU - Driss Kaddar
AU - Andrew J. Aspden
AU - Thomas L. Howarth
AU - Christian Hasse
AU - Hendrik Nicolai
PY - 2026
DA - 2026/10/27
PB - arXiv
DO - 10.48550/arxiv.2610.37577
UR - https://arxiv.org/abs/2610.37577
AB - The Artificially Thickened Flame (ATF) approach is widely used to render premixed flames resolvable on coarse computational meshes, but thickening alters their interaction with turbulence. While considerable research has focused on the effects of thickening on turbulence-induced flame wrinkling, its influence on the mean local flame propagation speed in turbulent, thermodiffusively unstable hydrogen flames remains poorly understood. More than 200 flame-resolved simulations of premixed flames in homogeneous isotropic turbulence with detailed chemistry and transport are used to systematically isolate and quantify the effects of artificial thickening. Thickening the flame by a factor F increases its effective flame-scale Karlovitz number according to Ka_f^F = Ka_f√F, while decreasing its effective Damköhler number according to Da_f^F = Da_f/F. In the regime considered here, the former enhances the mean local flame speed, whereas the latter reduces flame wrinkling, resulting in opposing effects on the flame consumption speed; hence, changes in both local flame propagation and flame area must be accounted for. Simulations matched with respect to Ka_f^F and Da_f^F collapse across different thickening factors F until the thickened flame approaches the integral or geometric length scales of the configuration. Based on these scaling relations, a self-consistent efficiency correction is proposed to recover the unthickened flame consumption speed. Since the efficiency factor feeds back on the effective Karlovitz and Damköhler numbers, it must be determined implicitly.
ER -