On the Use of Semi-empirical Flame Models for Spreading Chaparral Crown Fire

Cobian-Iñiguez, Jeanette; Aminfar, AmirHessam; Weise, David R.; Princevac, Marko

doi:10.3389/fmech.2019.00050

Cited by 9 publications

(5 citation statements)

References 36 publications

(52 reference statements)

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“…Personal communication, John Maitland, Chief, Forestry Branch, USAG Ft. Jackson to David Weise, 2015. While Fire 2022, 5, 118 sparkleberry was the focus of the present study, Wenk et al [58] found similar results in another prescribed fire study in the Carolina sandhills in longleaf stands where turkey oak (Quercus laevis) was the dominant understory woody plant [59][60][61][62]. It is well-established that natural fuel loadings are highly variable, particularly in forested systems with an understory component [63][64][65].…”

Section: Fuel Density/consumption Estimatessupporting

confidence: 72%

Point Cloud Based Mapping of Understory Shrub Fuel Distribution, Estimation of Fuel Consumption and Relationship to Pyrolysis Gas Emissions on Experimental Prescribed Burns

Herzog

Hudak

Weise

et al. 2022

Fire

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Forest fires spread via production and combustion of pyrolysis gases in the understory. The goal of the present paper is to understand the spatial location, distribution, and fraction (relative to the overstory) of understory plants, in this case, sparkleberry shrub, namely its degree of understory consumption upon burn, and to search for correlations between the degree of shrub consumption to the composition of emitted pyrolysis gases. Data were collected in situ at seven small experimental prescribed burns at Ft. Jackson, an army base in South Carolina, USA. Using airborne laser scanning (ALS) to map overstory tree crowns and terrestrial laser scanning (TLS) to characterize understory shrub fuel density, both pre- and postburn estimates of sparkleberry coverage were obtained. Sparkleberry clump polygons were manually digitized from a UAV-derived orthoimage of the understory and intersected with the TLS point cloud-derived rasters of pre- and postburn shrub fuel bulk density; these were compared in relation to overstory crown cover as well as to ground truth. Shrub fuel consumption was estimated from the digitized images; sparkleberry clump distributions were generally found to not correlate well to the overstory tree crowns, suggesting it is shade-tolerant. Moreover, no relationship was found between the magnitude of the fuel consumption and the chemical composition of pyrolysis gases, even though mixing ratios of 25 individual gases were measured.

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Section: Fuel Density/consumption Estimatessupporting

confidence: 72%

Point Cloud Based Mapping of Understory Shrub Fuel Distribution, Estimation of Fuel Consumption and Relationship to Pyrolysis Gas Emissions on Experimental Prescribed Burns

Herzog

Hudak

Weise

et al. 2022

Fire

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“…These correlations can then be used to derive coefficients for models through regression analysis. This approach has been successfully applied in studies of chaparral crown fires, thus demonstrating the applicability of semi-empirical models in diverse fire scenarios [34]. The plot depicts the dynamics of v, thereby highlighting its behavior over the adjusted time and space range.…”

Section: Profiles Of Analytical Solutionsmentioning

confidence: 92%

Analytical and Computational Approaches for Bi-Stable Reaction and p-Laplacian Diffusion Flame Dynamics in Porous Media

Rahman,

Díaz Palencia

2024

Mathematics

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In this paper, we present a mathematical approach for studying the changes in pressure and temperature variables in flames. This conception extends beyond the traditional second-order Laplacian diffusion model by considering the p-Laplacian operator and a bi-stable reaction term, thereby providing a more generalized framework for flame diffusion analysis. Given the structure of our equations, we provide the boundedness and uniqueness of the solutions in a weak sense from both analytical and numerical approaches. We further reformulate the governing equations in the context of traveling wave solutions, applying singular geometric perturbation theory to derive the analytical expressions of these profiles. This theoretical development is complemented by numerical assessments, which not only validate our theoretical predictions, but also optimize the traveling wave speed to minimize the error between numerical and analytical solutions. Additionally, we explore self-similar structured solutions. The paper then concludes with a perspective on future research, with emphasis being placed on the need for experimental validation in laboratory settings. Such empirical studies could test the robustness of our model and allow for refinement based on actual measurements, thereby broadening the applicability and accuracy of our findings in practical scenarios.

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“…The data inside the threshold contour takes the value one and the data outside the threshold contour takes the value zero. Following [37], an ellipse is fitted to the binary image at every time level using the MATLAB function regionprops. The ellipse is constrained so that the second moment of the ellipse is equal to the second moment of the nonzero region of the image.…”

Section: Determination Of Flame Lengthmentioning

confidence: 99%

Field-Scale Physical Modelling of Grassfire Propagation on Sloped Terrain under Low-Speed Driving Wind

Innocent,

Sutherland,

Moinuddin

2023

Fire

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Driving wind and slope of terrain can increase the rate of surface fire propagation. Previous physical modelling under higher driving wind (3–12.5 m/s) on slopes (Innocent et al., IJWF, 2023, 32(4), pp. 496–512 and 513–530) demonstrated that the averaged rate of fire spread (RoS) varied from that of empirical models. This study investigates the potential for better agreement at lower wind velocities (0.1 and 1 m/s), since empirical models are typically developed from experimental studies conducted under benign wind conditions. The same physical model WFDS is used. The results are analysed to understand the behaviour of various parameters (RoS, fire isochrone progression, fire intensity, flame dynamics, and heat fluxes) across different slopes. The RoS–slope angle relationship closely fits an exponential model, aligning with the findings from most experimental studies. The relative RoSs are aligned more closely with the Australian and Rothermel models’ slope corrections for 0.1 and 1 m/s, respectively. The relationship between flame length and fire intensity matches predictions from an empirical power–law correlation. Flame and plume dynamics reveal that the plume rises at a short distance from the ignition line and fire propagation is primarily buoyancy-driven. The Byram number analysis shows buoyancy-dominated fire propagation at these lower wind velocities. Convective heat fluxes are found to be more significant at greater upslopes. The study confirmed that “lighter & drier” fuel parameters accelerated the fire front movement, increasing the RoS by approximately 57–60% compared to the original parameters. Overall, this study underscores the nuanced interplay of wind speed, slope, and other factors in influencing grassfire behaviour, providing valuable insights for predictive modelling and firefighting strategies.

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On the Use of Semi-empirical Flame Models for Spreading Chaparral Crown Fire

Cited by 9 publications

References 36 publications

Point Cloud Based Mapping of Understory Shrub Fuel Distribution, Estimation of Fuel Consumption and Relationship to Pyrolysis Gas Emissions on Experimental Prescribed Burns

Point Cloud Based Mapping of Understory Shrub Fuel Distribution, Estimation of Fuel Consumption and Relationship to Pyrolysis Gas Emissions on Experimental Prescribed Burns

Analytical and Computational Approaches for Bi-Stable Reaction and p-Laplacian Diffusion Flame Dynamics in Porous Media

Field-Scale Physical Modelling of Grassfire Propagation on Sloped Terrain under Low-Speed Driving Wind

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