Premixed flames in a stagnation point flow under Darcy's law
Abstract
Premixed flames in stagnation point flows are traditionally described using Navier--Stokes equations where inertia and density variations play an important part in determining the flame structure. However, in porous media or Hele-Shaw configurations, Darcy's law replaces the momentum balance, shifting the governing physics to a balance between pressure and viscous forces. This study investigates non-adiabatic strained premixed flames under Darcy's law, pertinent in particular to confined flames in Hele-Shaw burners, accounting for non-unity Lewis numbers and volumetric heat losses. The flame is established in a planar counterflow formed by impinging a cold unburnt gas and a hot burnt gas maintained at the adiabatic flame temperature. We show that the jump in the strain rate across the flame is associated with a jump in viscosity, rather than, as in the classical Navier--Stokes case, a jump in density. Furthermore, the ratio of viscosity to the density-permeability product μ/ρκ, i.e., kinematic viscous resistance, is identified as a key coordinate stretching factor in the mathematical description of the flame structure. This ratio increases significantly across the flame. As a result: (1) the burnt gas acts as a strong viscous barrier, (2) for an increasing strain rate, flame migration towards the burnt gas is hindered, (3) for a decreasing strain rate, migration towards the unburnt gas is promoted, and (4) streamline refraction is augmented. By analysing the burning rate across varying strain rates and heat-loss parameters, we identify distinct extinction and ignition regimes that fundamentally differ from classical combustion theory, thereby providing new insights into flame stabilisation in friction-dominated environments and under confinement.
Versions
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BibTeX
@misc{rajamanickam2026premixed,
title = {{Premixed flames in a stagnation point flow under Darcy's law}},
author = {Prabakaran Rajamanickam and Joel Daou},
howpublished = {arXiv},
year = {2026},
month = sep,
doi = {10.48550/arxiv.2606.28909},
eprint = {2606.28909},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2606.28909},
}
RIS
TY - UNPB
TI - Premixed flames in a stagnation point flow under Darcy's law
AU - Prabakaran Rajamanickam
AU - Joel Daou
PY - 2026
DA - 2026/09/11
PB - arXiv
DO - 10.48550/arxiv.2606.28909
UR - https://arxiv.org/abs/2606.28909
AB - Premixed flames in stagnation point flows are traditionally described using Navier--Stokes equations where inertia and density variations play an important part in determining the flame structure. However, in porous media or Hele-Shaw configurations, Darcy's law replaces the momentum balance, shifting the governing physics to a balance between pressure and viscous forces. This study investigates non-adiabatic strained premixed flames under Darcy's law, pertinent in particular to confined flames in Hele-Shaw burners, accounting for non-unity Lewis numbers and volumetric heat losses. The flame is established in a planar counterflow formed by impinging a cold unburnt gas and a hot burnt gas maintained at the adiabatic flame temperature. We show that the jump in the strain rate across the flame is associated with a jump in viscosity, rather than, as in the classical Navier--Stokes case, a jump in density. Furthermore, the ratio of viscosity to the density-permeability product μ/ρκ, i.e., kinematic viscous resistance, is identified as a key coordinate stretching factor in the mathematical description of the flame structure. This ratio increases significantly across the flame. As a result: (1) the burnt gas acts as a strong viscous barrier, (2) for an increasing strain rate, flame migration towards the burnt gas is hindered, (3) for a decreasing strain rate, migration towards the unburnt gas is promoted, and (4) streamline refraction is augmented. By analysing the burning rate across varying strain rates and heat-loss parameters, we identify distinct extinction and ignition regimes that fundamentally differ from classical combustion theory, thereby providing new insights into flame stabilisation in friction-dominated environments and under confinement.
ER -