@article {bnh-8372, title = {Physics-based simulations of grassfire propagation on sloped terrain at field scale: flame dynamics, mode of fire propagation and heat fluxes}, journal = {International Journal of Wildland Fire}, year = {2023}, month = {01/2023}, abstract = {

The interaction of wind and fire on a sloped terrain is always complex owing to the mechanisms of heat transfer and flame dynamics. Heating of unburned vegetation by attached flames may increase the rate of spread. The relative intensities of convective and radiative heat fluxes may change fire behaviour significantly. This paper presents a detailed analysis of flame dynamics, mode of fire propagation and surface radiative and convective heat fluxes on sloped terrain at various wind speeds using physics-based simulations. It was found that with increasing slope angles and wind velocity, the plume inclines more towards the ground and becomes elongated in upslope cases, whereas in downslope cases, the plume rises from the ground earlier. For higher wind velocities, the flame and near-surface flame dynamics appear to show rising, even though the plume is attached. The flame contour results indicate that the near-surface flame dynamics are difficult to characterise using Byram{\textquoteright}s number. A power-law correlation was observed between the simulated flame lengths and fireline intensities. The convective heat fluxes are more relevant for wind-driven fire propagation and greater upslopes, whereas both fluxes are equally significant for lower driving wind velocities compared with higher wind velocities.

}, keywords = {Byram number, fire propagation, flame, grassfire, heat fluxes, plume, rate of spread (RoS), slope, wind velocity}, doi = {https://doi.org/10.1071/WF21125}, url = {https://www.publish.csiro.au/wf/WF21125$\#$FN1}, author = {Jasmine Innocent and Duncan Sutherland and Nazmul Khan and Khalid Moinuddin} } @article {bnh-8157, title = {Numerical study on effect of relative humidity (and fuel moisture) on modes of grassfire propagation}, journal = {Fire Safety Journal}, year = {2021}, month = {08/2021}, abstract = {

Relative humidity of air is directly related to fuel moisture. Fuel moisture is often considered as the index of flammability in the context of bushfire. Variation of relative humidity and fuel moisture is considered to have a significant effect on the rate of spread of grassfire propagation and fire intensity. In this study, four sets of grassfire simulations have been conducted: three sets with 210 mm high grass and another set with 175 mm high grass. For all sets, the ambient temperature was kept constant while relative humidity and fuel moisture were varied, with fuel moisture deduced from the McArthur MKV GFDI model. With 210 mm grass heights, driving wind velocities were varied. Lower relative humidity (and fuel moisture) was observed to lead to higher fire intensity and a faster rate of spread, which are intuitively expected. Byram number analysis showed that relative humidity (and fuel moisture) can lead to change in the fire propagation mode (wind-driven vs buoyancy-driven), but the greater factor is the wind velocity.

}, keywords = {Byram number, grassfire, Mode of fire propagation, Physics-based modelling, relative humidity}, doi = {https://doi.org/10.1016/j.firesaf.2021.103422}, url = {https://www.sciencedirect.com/science/article/abs/pii/S0379711221001636}, author = {Khalid Moinuddin and Nazmul Khan and Duncan Sutherland} } @article {bnh-7838, title = {A response to comments of Cruz et al. on: {\textquoteleft}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{\textquoteright}}, journal = {International Journal of Wildland Fire}, year = {2021}, month = {02/2021}, abstract = {

In response to Cruzet al.(2020b) (hereafter: CSG20), we would like to clarify that we are committed to further research into the mechanisms that drive fire spread in grassland fuels, and are open to making the most of synergies that exist between various programs of research. As demonstrated by Filippiet al.(2013), Kochanskiet al.(2013), Clementset al.(2019), etc., there is much to be gained by combining detailed experimental data with rigorous computational modelling.

}, keywords = {Byram number, fuel height, grass fire, modes of fire propagation, rate of spread.}, doi = {https://doi.org/10.1071/WF20091}, url = {https://www.publish.csiro.au/WF/WF20091}, author = {Duncan Sutherland and Jason J. Sharples and William Mell and Khalid Moinuddin} }