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arxiv: 2606.10188 · v1 · pith:A6BAN54W · submitted 2026-06-08 · physics.flu-dyn

Effect of a magnetostatic field on laminar premixed hydrogen-air flames

Tristan Lapaire , Sofiane Al Kassar , Antonio Attili , Andrea Giusti This is my paper

Reviewed by Pith2026-06-27 14:34 UTCgrok-4.3pith:A6BAN54Wopen to challenge →

classification physics.flu-dyn
keywords premixed hydrogen-air flamesmagnetostatic fieldshydrodynamic instabilitiesdirect numerical simulationsflame areavorticitypressure dependenceflame consumption speed
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The pith

Magnetostatic fields reduce consumption speed of premixed hydrogen-air flames by closing instability structures through changes in flow vorticity.

A machine-rendered reading of the paper's core claim, the machinery that carries it, and where it could break.

This paper uses direct numerical simulations to examine how magnetostatic fields influence laminar premixed hydrogen-air flames that develop hydrodynamic instabilities. The central finding is that magnetic forces can substantially decrease the flame consumption speed at atmospheric pressure by reducing the flame area, while having little effect at high pressure. The key mechanism is the rotational component of these forces modifying the flow's vorticity, which causes the finger-like structures from instabilities to close. Effects on the flame's chemical reactivity and small cellular structures are shown to be negligible. The results point to a potential method for controlling flame behavior using magnetic fields.

Core claim

Direct numerical simulations demonstrate that configurations of magnetostatic fields with gradients oriented opposite to the incoming reactant flow reduce the flame consumption speed, an effect substantial at atmospheric conditions but negligible at high pressure and temperature. This reduction is primarily due to a decrease in flame area rather than changes in local reactivity. Analysis of force contributions shows that the rotational component of the magnetic forces alters the vorticity of the flow, causing finger-like structures formed by hydrodynamic instabilities to close. The magnetic forces are significant at low pressure but become negligible compared to the pressure gradient at high

What carries the argument

The rotational component of the magnetic body forces, which alters the vorticity of the flow to close finger-like instability structures.

Load-bearing premise

The simulations assume that magnetic body forces can be added directly to the momentum equations and that the chosen field gradients capture the dominant interactions without significant unmodeled effects.

What would settle it

A direct numerical simulation or experiment at low pressure that shows no alteration in flow vorticity or no closing of finger-like structures under the applied magnetic field gradient would falsify the mechanism.

Figures

Figures reproduced from arXiv: 2606.10188 by Andrea Giusti, Antonio Attili, Sofiane Al Kassar, Tristan Lapaire.

Figure 1
Figure 1. Figure 1: Simulation domain and gradient of the square of the magnetic field for configurations (b)–(e). The domain is 200 x 200 [PITH_FULL_IMAGE:figures/full_fig_p002_1.png] view at source ↗
Figure 2
Figure 2. Figure 2: Time-averaged non-dimensional flame consumption speed (left), flame surface (middle), and stretch factor (right) for [PITH_FULL_IMAGE:figures/full_fig_p004_2.png] view at source ↗
Figure 3
Figure 3. Figure 3: Logarithmic joint probability density function of the [PITH_FULL_IMAGE:figures/full_fig_p004_3.png] view at source ↗
Figure 4
Figure 4. Figure 4: Probability density function of the reduced radius of [PITH_FULL_IMAGE:figures/full_fig_p005_4.png] view at source ↗
Figure 5
Figure 5. Figure 5: Logarithmic joint probability density functions of the [PITH_FULL_IMAGE:figures/full_fig_p005_5.png] view at source ↗
Figure 7
Figure 7. Figure 7: Instantaneous fields at t ≈ 200 τf for Case 1 and magnetic field configuration (e); x-component (top row) and y￾component (bottom row) of the pressure gradient ∇Pk, the total Kelvin force density fKB2 , the difference ∇Pk − f irr KB2 , and the rotational component f rot KB2 . ysed in [PITH_FULL_IMAGE:figures/full_fig_p006_7.png] view at source ↗
Figure 8
Figure 8. Figure 8: Logarithmic joint probability density functions of the various contributions to the [PITH_FULL_IMAGE:figures/full_fig_p007_8.png] view at source ↗
Figure 9
Figure 9. Figure 9: Logarithmic joint probability density function of the [PITH_FULL_IMAGE:figures/full_fig_p008_9.png] view at source ↗
read the original abstract

Magnetic fields have shown potential to affect flame characteristics; however, the mechanisms of interaction are not fully understood. This paper investigates the effect of magnetic fields on premixed hydrogen-air flames that are prone to intrinsic instabilities, with a focus on the role of magnetic forces on the flame behaviour. The study is conducted using direct numerical simulations. Two flame conditions, both with an equivalence ratio of 0.5, are studied, one with the reactants at atmospheric conditions and the other at high pressure and high temperature. Different configurations of the magnetic field are investigated, each characterised by a different gradient of the square of the magnitude of the magnetic field, oriented in the direction opposite to the velocity of the incoming reactants. Results show that the investigated configurations of the magnetic field can reduce the flame consumption speed, an effect that is substantial in the lower pressure case, while it becomes negligible at high pressure. The effect of the magnetic forces increases with increasing gradient of the magnetic field and is mainly due to the reduction of the flame area. Results also show that the effects of magnetic fields on the reactivity of the flame and on the small cell structures developed along the flame front are negligible. Analysis of the force contributions demonstrates that the change in the flame area is caused by the rotational component of the magnetic forces, which alter the vorticity of the flow such that the finger-like structures formed by hydrodynamic instabilities tend to close. These forces are significant at low pressure, while they become negligible compared to the pressure gradient at high pressure. Ultimately, the results of this work indicate that magnetic forces have the potential to change the flame behaviour, a mechanism that could be used for active control of flames.

Editorial analysis

A structured set of objections, weighed in public.

Desk editor's note, referee report, simulated authors' rebuttal, and a circularity audit. Tearing a paper down is the easy half of reading it; the pith above is the substance, this is the friction.

Referee Report

2 major / 2 minor

Summary. The paper uses direct numerical simulations of laminar premixed hydrogen-air flames (ϕ=0.5) at atmospheric and elevated pressure to examine the influence of imposed magnetostatic field gradients oriented against the reactant flow. It reports that the magnetic body force reduces consumption speed primarily by decreasing flame area, an effect attributed to the rotational component of the force altering flow vorticity and closing hydrodynamic finger structures; the influence is substantial at low pressure but negligible at high pressure relative to the pressure gradient.

Significance. If the force implementation and analysis are correct, the work supplies a mechanistic explanation for magnetic modification of intrinsically unstable flames and identifies a pressure-dependent regime where such control may be feasible. The DNS-based decomposition of force contributions and vorticity budgets provides concrete, falsifiable evidence for the proposed rotational mechanism.

major comments (2)
  1. [Numerical methods / magnetic-force implementation] The manuscript does not state whether the magnetic susceptibility χ is treated as a constant or as a local function of temperature and mixture composition. The central claim that the rotational component of F_mag alters vorticity (and thereby closes fingers) requires curl(F_mag) ≠ 0 inside the flame; this occurs only when χ varies spatially. A constant-χ implementation would make the rotational term identically zero, rendering the force analysis unable to demonstrate causation.
  2. [Results / force-contribution analysis] The low-pressure versus high-pressure comparison of |F_mag| versus ∇p assumes that the modeled force scales correctly with the changes in density and flame thickness. Without an explicit expression for χ(T,Y_i) or a verification that the mixture-averaged formulation is used, it is impossible to confirm that the reported pressure dependence is physical rather than an artifact of the chosen body-force implementation.
minor comments (2)
  1. [Abstract and §3] The abstract and results refer to “different configurations of the magnetic field” characterized by gradients of B²; the precise functional forms and magnitudes of these gradients should be stated explicitly, preferably with an equation or table.
  2. [Figures and results text] Figure captions and text should clarify whether the reported consumption speeds are normalized by the laminar flame speed or by an effective speed that already incorporates area changes.

Simulated Author's Rebuttal

2 responses · 0 unresolved

We thank the referee for the careful reading and constructive comments on the magnetic-force implementation. We address each major comment below.

read point-by-point responses

  1. Referee: [Numerical methods / magnetic-force implementation] The manuscript does not state whether the magnetic susceptibility χ is treated as a constant or as a local function of temperature and mixture composition. The central claim that the rotational component of F_mag alters vorticity (and thereby closes fingers) requires curl(F_mag) ≠ 0 inside the flame; this occurs only when χ varies spatially. A constant-χ implementation would make the rotational term identically zero, rendering the force analysis unable to demonstrate causation.

    Authors: We agree that the treatment of χ must be stated explicitly. χ was implemented as a local function of temperature and mixture composition via the mixture-averaged formulation for paramagnetic and diamagnetic species. We will add the explicit expression χ(T, Y_i) and confirm that curl(F_mag) is nonzero inside the flame front, supporting the rotational mechanism. revision: yes

  2. Referee: [Results / force-contribution analysis] The low-pressure versus high-pressure comparison of |F_mag| versus ∇p assumes that the modeled force scales correctly with the changes in density and flame thickness. Without an explicit expression for χ(T,Y_i) or a verification that the mixture-averaged formulation is used, it is impossible to confirm that the reported pressure dependence is physical rather than an artifact of the chosen body-force implementation.

    Authors: We will add the explicit χ(T, Y_i) expression and verify the mixture-averaged formulation in the methods section. We will also include a brief scaling analysis confirming that the |F_mag| versus ∇p comparison follows from the physical changes in density and flame thickness between the two cases. revision: yes

Circularity Check

0 steps flagged

No circularity: results from direct numerical simulation of governing equations with added magnetic terms

full rationale

The paper reports DNS of hydrogen-air flames with magnetostatic body forces added to the momentum equation. Claims about rotational force components altering vorticity and closing hydrodynamic structures are obtained by post-processing the simulation fields (force budgets, flame area, consumption speed). No parameters are fitted to data and then re-predicted, no self-definitional loops appear in the governing equations or analysis, and no load-bearing uniqueness theorems or ansatzes are imported via self-citation. The low-pressure vs. high-pressure comparison follows directly from the solved equations under the stated conditions.

Axiom & Free-Parameter Ledger

0 free parameters · 1 axioms · 0 invented entities

The study rests on standard assumptions of direct numerical simulation for low-Mach reacting flows with added magnetic body forces; no free parameters, new entities, or ad-hoc axioms are introduced beyond the simulation framework itself.

axioms (1)
  • domain assumption Direct numerical simulation of the Navier-Stokes equations with added magnetic body forces accurately captures the interaction between magnetostatic fields and hydrodynamic instabilities in premixed flames.
    The entire investigation is performed using this numerical approach without additional validation steps reported in the abstract.

pith-pipeline@v0.9.1-grok · 5840 in / 1338 out tokens · 29825 ms · 2026-06-27T14:34:01.004597+00:00 · methodology

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Reference graph

Works this paper leans on

40 extracted references

  1. [1]

    Fontecave, S

    M. Fontecave, S. Candel, T. Poinsot, Hydrogen to- day and tomorrow, Tech. rep., Acad´emie des sciences (2024)

    2024

  2. [2]

    Darrieus, Propagation d’un front de flamme, La Technique Moderne 30 (18) (1938)

    G. Darrieus, Propagation d’un front de flamme, La Technique Moderne 30 (18) (1938)

    1938

  3. [3]

    C. K. Law, Combustion physics, Cambridge university press, 2010

    2010

  4. [4]

    Matalon, Intrinsic flame instabilities in premixed and nonpremixed combustion, Annu

    M. Matalon, Intrinsic flame instabilities in premixed and nonpremixed combustion, Annu. Rev. Fluid Mech. 39 (1) (2007) 163–191

    2007

  5. [5]

    Matalon, The darrieus–landau instability of pre- mixed flames, Fluid Dynamics Research 50 (5) (2018) 051412

    M. Matalon, The darrieus–landau instability of pre- mixed flames, Fluid Dynamics Research 50 (5) (2018) 051412

    2018

  6. [6]

    Altantzis, C

    C. Altantzis, C. Frouzakis, A. Tomboulides, M. Mat- alon, K. Boulouchos, Hydrodynamic and thermodiffu- sive instability effects on the evolution of laminar pla- nar lean premixed hydrogen flames, Journal of fluid mechanics 700 (2012) 329–361

    2012

  7. [7]

    Berger, K

    L. Berger, K. Kleinheinz, A. Attili, H. Pitsch, Char- acteristic patterns of thermodiffusively unstable pre- mixed lean hydrogen flames, Proceedings of the Com- bustion Institute 37 (2) (2019) 1879–1886

    2019

  8. [8]

    Berger, A

    L. Berger, A. Attili, H. Pitsch, Intrinsic instabilities in premixed hydrogen flames: Parametric variation of pressure, equivalence ratio, and temperature. part 1 - dispersion relations in the linear regime, Combustion and Flame 240 (2022) 111935

    2022

  9. [9]

    Berger, A

    L. Berger, A. Attili, H. Pitsch, Intrinsic instabilities in premixed hydrogen flames: parametric variation of pressure, equivalence ratio, and temperature. part 2 – non-linear regime and flame speed enhancement, Combustion and Flame 240 (2022) 111936

    2022

  10. [10]

    Faraday, Lxiv

    M. Faraday, Lxiv. on the diamagnetic conditions of flame and gases, The London, Edinburgh, and Dublin Philosophical Magazine and Journal of Science 31 (210) (1847) 401–421

  11. [11]

    Mizutani, M

    Y . Mizutani, M. Fuchihata, Y . Ohkura, Pre-mixed lam- inar flames in a uniform magnetic field, Combustion and flame 125 (1-2) (2001) 1071–1073

    2001

  12. [12]

    N. I. Wakayama, Behavior of gas flow under gradi- ent magnetic fields, Journal of Applied Physics 69 (4) (1991) 2734–2736

    1991

  13. [13]

    N. I. Wakayama, Magnetic acceleration and decelera- tion of o2 gas streams injected into air, IEEE transac- tions on magnetics 31 (1) (1995) 897–901

    1995

  14. [14]

    Yamada, M

    E. Yamada, M. Shinoda, H. Yamashita, K. Kitagawa, Numerical analysis of a hydrogen-oxygen diffusion flame in vertical or horizontal gradient of magnetic field, Combustion science and technology 174 (9) (2002) 149–164

    2002

  15. [15]

    Yamada, M

    E. Yamada, M. Shinoda, H. Yamashita, K. Kitagawa, Experimental and numerical analyses of magnetic ef- fect on oh radical distribution in a hydrogen-oxygen diffusion flame, Combustion and flame 135 (4) (2003) 365–379

    2003

  16. [16]

    Kinoshita, T

    S. Kinoshita, T. Takagi, H. Kotera, N. I. Wakayama, Numerical simulation of diffusion flames with and without magnetic field, IEEE transactions on applied superconductivity 14 (2) (2004) 1685–1688

    2004

  17. [17]

    Hosseinpour, H

    J. Hosseinpour, H. Mahdavy-Moghaddam, Computa- tional study of magnetic field effects on the nozzle of hydrogen micro flame, Combustion and Flame 220 (2020) 247–256

    2020

  18. [18]

    V . M. Natesh, I. Langella, Influence of magnetic field on flame dynamics in hydrogen flames: A numeri- cal study, Proceedings of the Combustion Institute 41 (2025) 105892

    2025

  19. [19]

    Ortner, L

    M. Ortner, L. G. C. Bandeira, Magpylib: A free python package for magnetic field computation, SoftwareX 11 (2020) 100466

    2020

  20. [20]

    Al Kassar, L

    S. Al Kassar, L. Berger, P. E. Lapenna, F. Creta, H. Pitsch, A. Attili, Efficient and accurate calcula- tion of dispersion relations for intrinsically unstable premixed flames, Combustion and Flame 269 (2024) 113640

    2024

  21. [21]

    Tomboulides, J

    A. Tomboulides, J. Lee, S. Orszag, Numerical simu- lation of low mach number reactive flows, Journal of Scientific Computing 12 (1997) 139–167

    1997

  22. [22]

    M. P. Burke, M. Chaos, Y . Ju, F. L. Dryer, S. J. Klippenstein, Comprehensive h2/o2 kinetic model for high-pressure combustion, International Journal of Chemical Kinetics 44 (7) (2012) 444–474

    2012

  23. [23]

    C. R. Wilke, A viscosity equation for gas mixtures, Journal of Chemical physics 18 (4) (1950) 517–519

    1950

  24. [24]

    R. B. Bird, Transport phenomena, Appl. Mech. Rev. 55 (1) (2002) R1–R4

    2002

  25. [25]

    Attili, F

    A. Attili, F. Bisetti, M. E. Mueller, H. Pitsch, Effects of non-unity lewis number of gas-phase species in tur- bulent nonpremixed sooting flames, Combustion and Flame 166 (2016) 192–202

    2016

  26. [26]

    F. A. Williams, Combustion theory, 2nd Edition, CRC Press, 2018

    2018

  27. [27]

    J. O. Hirschfelder, C. F. Curtiss, R. B. Bird, The molec- ular theory of gases and liquids, John Wiley & Sons, 1964

    1964

  28. [28]

    Zirwes, A

    T. Zirwes, A. Kronenburg, Assessment of approxi- mate soret diffusion models for hydrogen and am- monia combustion, Flow, Turbulence and Combustion (2025) 1–20

    2025

  29. [29]

    Desjardins, G

    O. Desjardins, G. Blanquart, G. Balarac, H. Pitsch, High order conservative finite difference scheme for variable density low mach number turbulent flows, Journal of Computational Physics 227 (15) (2008) 7125–7159

    2008

  30. [30]

    Niemietz, L

    K. Niemietz, L. Berger, M. Huth, A. Attili, H. Pitsch, Direct numerical simulation of flame-wall interaction at gas turbine relevant conditions, Proceedings of the Combustion Institute 39 (2) (2023) 2209–2218

    2023

  31. [31]

    X.-D. Liu, S. Osher, T. Chan, Weighted essentially non-oscillatory schemes, Journal of Computational Physics 115 (1) (1994) 200–212

    1994

  32. [32]

    A. C. Hindmarsh, P. N. Brown, K. E. Grant, S. L. Lee, R. Serban, D. E. Shumaker, C. S. Woodward, Sundi- als: Suite of nonlinear and differential/algebraic equa- tion solvers, ACM Trans. Math. Softw. 31 (3) (2005) 363–396

    2005

  33. [33]

    James R., Continuum Electromechanics, Cam- bridge, MA: MIT Press, Copyright Massachusetts In- stitute of Technology, 1981

    M. James R., Continuum Electromechanics, Cam- bridge, MA: MIT Press, Copyright Massachusetts In- stitute of Technology, 1981

    1981

  34. [34]

    Curie, Propri ´et´es magn´etiques des corps a diverses temp´eratures, Gauthier-Villars et fils, 1895

    P. Curie, Propri ´et´es magn´etiques des corps a diverses temp´eratures, Gauthier-Villars et fils, 1895

  35. [35]

    G. M. Barrow, Physical Chemistry, 6th Edition, McGraw-Hill, 1996

    1996

  36. [36]

    Herzberg, Atomic spectra and atomic structure, Dover, 1944

    G. Herzberg, Atomic spectra and atomic structure, Dover, 1944

    1944

  37. [37]

    G. K. Batchelor, An introduction to fluid dynamics, Cambridge university press, 2000

    2000

  38. [38]

    Berger, M

    L. Berger, M. Grinberg, B. J ¨urgens, P. E. Lapenna, F. Creta, A. Attili, H. Pitsch, Flame fingers and inter- actions of hydrodynamic and thermodiffusive instabil- ities in laminar lean hydrogen flames, Proceedings of the Combustion Institute 39 (2) (2023) 1525–1534

    2023

  39. [39]

    Berger, A

    L. Berger, A. Attili, M. Gauding, H. Pitsch, Effects of karlovitz number variations on thermodiffusive in- stabilities in lean turbulent hydrogen jet flames, Pro- ceedings of the Combustion Institute 40 (1-4) (2024) 105219

    2024

  40. [40]

    T. A. Butcher, J. M. D. Coey, Magnetic forces in para- magnetic fluids, Journal of Physics: Condensed Matter 35 (5) (2022) 053002. 10

    2022