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Wildfire models: Firebrands and cont...

Koo, Eunmo.

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Wildfire models: Firebrands and contiguous spread.

Record Type:	Electronic resources : Monograph/item
Title/Author:	Wildfire models: Firebrands and contiguous spread./
Author:	Koo, Eunmo.
Description:	237 p.
Notes:	Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4666.
Contained By:	Dissertation Abstracts International67-08B.
Subject:	Biology, Ecology. -
Online resource:	http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3228385
ISBN:	9780542825361

Wildfire models: Firebrands and contiguous spread.
Koo, Eunmo.

Wildfire models: Firebrands and contiguous spread. - 237 p.

Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4666.

Thesis (Ph.D.)--University of California, Berkeley, 2006.

Wildfires are a complex phenomenon. To understand their spread mechanisms, physics based wildfire models are developed here. Discontinuous fire spread, i.e., spotting, is studied through a review of historical wind-driven and post-earthquake fires. Transport of various shapes of combusting firebrands based is modeled using momentum balance on the firebrand. Firebrand trajectories are simulated in velocity and thermal fields generated by the FIRETEC wildfire model. Contiguous fire spread is modeled based on energy conservation and detailed heat transfer mechanisms. Predictions of contiguous fire spread rates are compared to laboratory experiments and prescribed fires.

ISBN: 9780542825361Subjects--Topical Terms:

1017726
Biology, Ecology.

Wildfire models: Firebrands and contiguous spread.
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035 $a (UMI)AAI3228385
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100 1 $a Koo, Eunmo. $3 1917831
245 1 0 $a Wildfire models: Firebrands and contiguous spread.
300 $a 237 p.
500 $a Source: Dissertation Abstracts International, Volume: 67-08, Section: B, page: 4666.
500 $a Adviser: Patrick J. Pagni.
502 $a Thesis (Ph.D.)--University of California, Berkeley, 2006.
520 $a Wildfires are a complex phenomenon. To understand their spread mechanisms, physics based wildfire models are developed here. Discontinuous fire spread, i.e., spotting, is studied through a review of historical wind-driven and post-earthquake fires. Transport of various shapes of combusting firebrands based is modeled using momentum balance on the firebrand. Firebrand trajectories are simulated in velocity and thermal fields generated by the FIRETEC wildfire model. Contiguous fire spread is modeled based on energy conservation and detailed heat transfer mechanisms. Predictions of contiguous fire spread rates are compared to laboratory experiments and prescribed fires.
520 $a Disk and cylinder firebrand histories are modeled in grassland fires with 1m/s, 3m/s, and 6m/s winds and in forest fires either with a full canopy or a partially open canopy with 6m/s wind on a 320mx320m flat terrain domain. Firebrand size distributions and travel distances are obtained. Firebrand launching sizes are assumed to be the local maximum loftable sizes based on the vertical wind velocity in each computational cell, which have longer lifetimes and further travel distances. Burnout effects are significant in the simulations. Disks are found to be aerodynamically more efficient than cylinders. Strong winds make firebrands travel further. However, they elongate flight times and accelerate burning rates, so that the transported mass of firebrands drops as wind speed increases. Maximum loftable size distributions are found to depend primarily on fuel conditions, while the travel distances depend strongly on the ambient wind speed. As expected, spot fire hazards in grassland fires are observed to be lower than in forest fires. The patchy canopy is found to be able to transport a firebrand further. However, the full forest was found to produce a larger number of firebrands which land in unburned fuel.
520 $a A simple physical model for contiguous fire spread is presented for the limit of one-dimensional steady-state contiguous spread of a line fire in a thermally-thin uniform porous fuel bed. The solution for the fire spread rate is found as an eigenvalue from the model with appropriate boundary conditions through a fourth order Runge-Kutta numerical method. Comparisons with laboratory experiments on white birch sticks and grassland fuel show that the physics in the model successfully incorporates the effects of wind, slope and fuel characteristics into the fire spread rate. Comparisons with data on a shrub fire in China and the prescribed chaparral fire in California also show good agreement. These comparisons suggest that this model may provide input to an improved operational model.
590 $a School code: 0028.
650 4 $a Biology, Ecology. $3 1017726
650 4 $a Agriculture, Forestry and Wildlife. $3 783690
650 4 $a Engineering, Mechanical. $3 783786
690 $a 0329
690 $a 0478
690 $a 0548
710 2 0 $a University of California, Berkeley. $3 687832
773 0 $t Dissertation Abstracts International $g 67-08B.
790 1 0 $a Pagni, Patrick J., $e advisor
790 $a 0028
791 $a Ph.D.
792 $a 2006
856 4 0 $u http://pqdd.sinica.edu.tw/twdaoapp/servlet/advanced?query=3228385