The correlation between wind and convective heat transfer in a propagating fire

M. S. Sadeghi; Maryam Ghodrat; Duncan Sutherland; Albert Simeoni; Harald Kleine

doi:10.1071/WF25099

RESEARCH ARTICLE (Open Access)

Previous Next Contents Vol 34(10)

The correlation between wind and convective heat transfer in a propagating fire

M. S. Sadeghi ^A ^* , Maryam Ghodrat

^A ^* , Duncan Sutherland ^B , Albert Simeoni ^C and Harald Kleine ^A

+ Author Affiliations

- Author Affiliations

^A School of Engineering and Technology, University of New South Wales (UNSW) Canberra, Australia.

^B School of Science, University of New South Wales (UNSW) Canberra, Australia.

^C Department of Fire Protection Engineering, Worcester Polytechnic Institute, 100 Institute Road, Worcester, MA 01605, USA.

^* Correspondence to: mohamad.sadeghi@unsw.edu.au, m.ghodrat@unsw.edu.au

International Journal of Wildland Fire 34, WF25099 https://doi.org/10.1071/WF25099

Submitted: 24 April 2025 Accepted: 16 September 2025 Published: 17 October 2025

© 2025 The Author(s) (or their employer(s)). Published by CSIRO Publishing on behalf of IAWF. This is an open access article distributed under the Creative Commons Attribution-NonCommercial-NoDerivatives 4.0 International License (CC BY-NC-ND)

Abstract

Background

Wind speed is one of the major parameters that affect fire rate of spread and heat transfer in propagating bushfires.

Aims

Laboratory-scale experiments and physics-based simulations are used to derive a correlation between wind speed and convective heating and cooling of surface fuels in bushfire scenarios.

Methods

A low-speed wind tunnel was designed and built to conduct fire spread experiments using Excelsior fuel on a level test bed, with a packing ratio 0.03 and a moisture content of 10%. The wind speed was varied between 0 and 3.3 m s⁻¹. Heat flux gauges and the retroreflective shadowgraph (RS) technique were used simultaneously to measure and visualise convective heat transfer. Simulations were conducted using the Fire Dynamics Simulator (FDS) to replicate the experimental study, enabling a detailed exploration of heat transfer modelling within the FDS framework.

Key results

The relationship between convective heat transfer and factors such as wind speed, flame angle, flame length and distance from the flame front was analysed and derived.

Implications

The results of this analysis reveal the mechanism of local convective heat transfer to downstream vegetation.

Keywords: Australian grass, convective cooling, convective heating, direct measurement, FDS, Fire Dynamics Simulator, fire ROS, retroreflective shadowgraph.

References

Albini FA (1985) A model for fire spread in wildland fuels by radiation. Combustion Science and Technology 42(4–6), 229-258.
| Crossref | Google Scholar |

Aminfar A, Cobian-Iñiguez J, Ghasemian M, Rosales Espitia N, Weise DR, Princevac M (2020) Using background-oriented schlieren to visualize convection in a propagating wildland fire. Combustion Science and Technology 192, 2259-2279.
| Crossref | Google Scholar |

Anderson WR, Catchpole EA, Butler BW (2010) Convective heat transfer in fire spread through fine fuel beds. International Journal of Wildland Fire 19(3), 284-298.
| Crossref | Google Scholar |

Apte VB, Bilger RW, Green AR, Quintiere JG (1991) Wind-aided turbulent flame spread and burning over large-scale horizontal PMMA surfaces. Combustion and Flame 85(1–2), 169-184.
| Crossref | Google Scholar |

Australian Institute of Health and Welfare (2020) Australian Bushfires 2019–20: Exploring the Short-term Health Impacts. (Australian Institute of Health and Welfare)

Balbi J-H, Rossi J-L, Marcelli T, Santoni P-A (2007) A 3D physical real-time model of surface fires across fuel beds. Combustion Science and Technology 179(12), 2511-2537.
| Crossref | Google Scholar |

Balbi J-H, Morandini F, Silvani X, Filippi J-B, Rinieri F (2009) A physical model for wildland fires. Combustion and Flame 156(12), 2217-2230.
| Crossref | Google Scholar |

Balbi J-H, Rossi J-L, Marcelli T, Chatelon F-J (2010) Physical modeling of surface fire under nonparallel wind and slope conditions. Combustion Science and Technology 182(7), 922-939.
| Crossref | Google Scholar |

Balbi J-H, Chatelon F-J, Morvan D, Rossi J-L, Marcelli T, Morandini F (2020) A convective–radiative propagation model for wildland fires. International Journal of Wildland Fire 29(9), 723-738.
| Crossref | Google Scholar |

Canny J (1986) A computational approach to edge detection. IEEE Transactions on Pattern Analysis and Machine Intelligence 8(6), 679-698.
| Google Scholar | PubMed |

Castro Rego FMC, Moreno Rodriguez JM, Vallejo Calzada VR, Xanthopoulos G (2018) ‘Forest fires – sparking fire-smart policies in the EU.’ (Publications Office of the European Union)

Chatelon FJ, Balbi JH, Cruz MG, Morvan D, Rossi JL, Awad C, Frangieh N, Fayad J, Marcelli T (2022) Extension of the Balbi fire spread model to include the field scale conditions of shrubland fires. International Journal of Wildland Fire 31(2), 176-192.
| Crossref | Google Scholar |

Cheney NP, Gould JS, Catchpole WR (1993) The influence of fuel, weather, and fire shape variables on fire-spread in grasslands. International Journal of Wildland Fire 3(1), 31-44.
| Crossref | Google Scholar |

Clark TL, Radke L, Coen J, Middleton D (1999) Analysis of small-scale convective dynamics in a crown fire using infrared video camera imagery. Journal of Applied Meteorology 38(10), 1401-1420.
| Crossref | Google Scholar |

Di Cristina G, Kozhumal S, Simeoni A, Skowronski N, Rangwala A, Im SK (2021) Forced convection fire spread along wooden dowel array. Fire Safety Journal 120, 103090.
| Crossref | Google Scholar |

Finlay SE, Moffat A, Gazzard R, Baker D, Murray V (2012) Health impacts of wildfires. PLoS Currents 4, e4f959951cce2c.
| Crossref | Google Scholar | PubMed |

Finney MA, Cohen JD, Forthofer JM, McAllister SS, Gollner MJ, Gorham DJ, Saito K, Akafuah NK, Adam BA, English JD (2015) Role of buoyant flame dynamics in wildfire spread. Proceedings of the National Academy of Sciences 112(32), 9833-9838.
| Crossref | Google Scholar | PubMed |

Frangieh N, Morvan D, Meradji S, Accary G, Bessonov O (2018) Numerical simulation of grassland fire behaviour using an implicit physical multiphase model. Fire Safety Journal 102, 37-47.
| Crossref | Google Scholar |

Gladstone JH, Dale TP (1863) XIV. Researches on the refraction, dispersion, and sensitiveness of liquids. Philosophical Transactions of the Royal Society of London 153, 317-343.
| Crossref | Google Scholar |

Grauer SJ, Unterberger A, Rittler A, Daun KJ, Kempf AM, Mohri K (2018) Instantaneous 3D flame imaging by background-oriented schlieren tomography. Combustion and Flame 196, 284-299.
| Crossref | Google Scholar |

Hargather MJ, Settles GS (2009) Retroreflective shadowgraph technique for large-scale flow visualization. Applied Optics 48(22), 4449-4457.
| Crossref | Google Scholar | PubMed |

Innocent J, Sutherland D, Khan N, Moinuddin K (2023) Physics-based simulations of grassfire propagation on sloped terrain at field scale: flame dynamics, mode of fire propagation and heat fluxes. International Journal of Wildland Fire 32(4), 513-530.
| Crossref | Google Scholar |

Jarrin N (2008) Synthetic inflow boundary conditions for the numerical simulation of turbulence. Doctoral dissertation, University of Manchester, United Kingdom.

Labahn JW, Wu H, Coriton B, Frank JH, Ihme M (2019) Data assimilation using high-speed measurements and LES to examine local extinction events in turbulent flames. Proceedings of the Combustion Institute 37(2), 2259-2266.
| Crossref | Google Scholar |

Linn RR, Cunningham P (2005) Numerical simulations of grass fires using a coupled atmosphere–fire model: basic fire behaviour and dependence on wind speed. Journal of Geophysical Research: Atmospheres 110, D13107.
| Crossref | Google Scholar |

McGrattan K, Hostikka S, McDermott R, Floyd J, Weinschenk C, Overholt K (2013a) ‘Fire Dynamics Simulator user’s guide. Vol. 1019(6).’ NIST Special Publication. pp. 1–339. (National Institute of Standards and Technology)

McGrattan K, Hostikka S, McDermott R, Floyd J, Weinschenk C, Overholt K (2013b) ‘Fire Dynamics Simulator Validation Guide.’ NIST Special Publication 1018-3, 6th edn. (National Institute of Standards and Technology)

McGrattan K, Hostikka S, McDermott R, Floyd J, Weinschenk C, Overholt K (2013c) ‘Fire Dynamics Simulator Technical Reference Guide Volume 1: Mathematical Model.’ NIST Special Publication, 1018-1, 6th edn. (National Institute of Standards and Technology)

Mell W, Jenkins MA, Gould J, Cheney P (2007) A physics-based approach to modelling grassland fires. International Journal of Wildland Fire 16(1), 1-22.
| Crossref | Google Scholar |

Mendes-Lopes JM, Ventura JM, Amaral JM (2003) Flame characteristics, temperature–time curves, and rate of spread in fires propagating in a bed of Pinus pinaster needles. International Journal of Wildland Fire 12(1), 67-84.
| Crossref | Google Scholar |

Moinuddin KAM, Sutherland D, Mell W (2018) Simulation study of grass fire using a physics-based model: striving towards numerical rigour and the effect of grass height on the rate of spread. International Journal of Wildland Fire 27, 800-814.
| Crossref | Google Scholar |

Morandini F, Simeoni A, Santoni PA, Balbi JH (2005) A model for the spread of fire across a fuel bed incorporating the effects of wind and slope. Combustion Science and Technology 177(7), 1381-1418.
| Crossref | Google Scholar |

Morvan D, Frangieh N (2018) Wildland fires behaviour: wind effect versus Byram’s convective number and consequences upon the regime of propagation. International Journal of Wildland Fire 27(9), 636-641.
| Crossref | Google Scholar |

Morvan D, Dupuy JL, Porterie B, Larini M (2000) Multiphase formulation applied to the modeling of fire spread through a forest fuel bed. Proceedings of the Combustion Institute 28, 2803-2809.
| Crossref | Google Scholar |

Mueller EV, Skowronski N, Thomas JC, Clark K, Gallagher MR, Hadden R, Mell W, Simeoni A (2018) Local measurements of wildland fire dynamics in a field-scale experiment. Combustion and Flame 194, 452-463.
| Crossref | Google Scholar |

Pagni PJ, Peterson TG (1973) Flame spread through porous fuels. Symposium (International) on Combustion 14, 1099-1107.
| Crossref | Google Scholar |

Sadeghi MS, Ghodrat M, Sutherland D, Simeoni A, Sharples J, Kleine H (2025a) Numerical investigation of the effect of wind, slope and fuel moisture on the radiative and convective heating of excelsior fuels. International Journal of Wildland Fire 34(4), WF24115.
| Crossref | Google Scholar |

Sadeghi MS, Ghodrat M, Sutherland D, Simeoni A, Kleine H (2025b) Comparison of background-oriented Schlieren and retroreflective shadowgraph visualizations of sand burner fire. Experimental Thermal and Fluid Science 169, 111569.
| Crossref | Google Scholar |

Santoni PA, Simeoni A, Rossi JL, Bosseur F, Morandini F, Silvani X, Balbi JH, Cancellieri D, Rossi L (2006) Instrumentation of wildland fire: characterisation of a fire spreading through a Mediterranean shrub. Fire Safety Journal 41(3), 171-184.
| Crossref | Google Scholar |

Settles GS (2001) ‘Schlieren and Shadowgraph Techniques: Visualizing Phenomena in Transparent Media.’ (Springer)

Settles GS, Hargather M (2017) A review of recent developments in schlieren and shadowgraph techniques. Measurement Science and Technology 28(4), 42001.
| Crossref | Google Scholar |

Singh A, Ziazi RM, Simeoni A (2023) Intermittent fireline behaviour over porous vegetative media in different crossflow conditions. International Journal of Wildland Fire 32(6), 998-1010.
| Crossref | Google Scholar |

Sullivan AL (2009a) Wildland surface fire spread modelling, 1990–2007. 1: Physical and quasi-physical models. International Journal of Wildland Fire 18, 349-368.
| Crossref | Google Scholar |

Sullivan AL (2009b) Wildland surface fire spread modelling, 1990–2007. 2: Empirical and quasi-empirical models. International Journal of Wildland Fire 18, 369-386.
| Crossref | Google Scholar |

Sullivan AL (2009c) Wildland surface fire spread modelling, 1990–2007. 3: Simulation and mathematical analogue models. International Journal of Wildland Fire 18, 387-403.
| Crossref | Google Scholar |

Sutherland D, Sharples JJ, Moinuddin KA (2019) The effect of ignition protocol on grassfire development. International Journal of Wildland Fire 29(1), 70-80.
| Crossref | Google Scholar |

Talluru KM, Kleine H (2022) Simultaneous background-oriented schlieren and retroreflective shadowgraph visualisation. Measurement Science and Technology 34(3), 35201.
| Crossref | Google Scholar |

Zhao K, Gollner MJ, Liu Q, Gong J, Yang L (2020) Lateral flame spread over PMMA under forced air flow. Fire Technology 56(2), 801-820.
| Crossref | Google Scholar |