@MastersThesis{Almeida:2007:MoPrFo,
author = "Almeida, Rodolfo Maduro",
title = "Modelo de propaga{\c{c}}{\~a}o de fogo em inc{\^e}ndios de
superf{\'{\i}}cie baseado no m{\'e}todo nodal",
school = "Instituto Nacional de Pesquisas Espaciais (INPE)",
year = "2007",
address = "S{\~a}o Jos{\'e} dos Campos",
month = "2007-02-28",
keywords = "Computa{\c{c}}{\~a}o aplicada, m{\'e}todo nodal, modelos
matem{\'a}ticos, inc{\^e}ndios florestais, forest fires, lumped
parameter systems, mathematical models.",
abstract = "Este trabalho prop{\~o}e um modelo de propaga{\c{c}}{\~a}o do
fogo aplic{\'a}vel a modelagem de inc{\^e}ndios florestais de
superf{\'{\i}}cie. A radia{\c{c}}{\~a}o emitida pela frente de
fogo e considerada como o principal mecanismo de
transfer{\^e}ncia de calor respons{\'a}vel pela
propaga{\c{c}}{\~a}o do fogo. As trocas de calor por
condu{\c{c}}{\~a}o, convec{\c{c}}{\~a}o e radia{\c{c}}{\~a}o
que ocorrem no interior do leito de combust{\'{\i}}vel s{\~a}o
aproximadas por um termo de condu{\c{c}}{\~a}o equivalente. A
abordagem matem{\'a}tica utilizada e o m{\'e}todo nodal.
Atrav{\'e}s dele, o leito de combust{\'{\i}}vel e subdividido
em um n{\'u}mero nito de regi{\~o}es, denominadas n{\'o}s. Cada
n{\'o} possui uma temperatura e propriedades t{\'e}rmicas
constantes. A chama sobre cada n{\'o} e aproximada por um
paralelep{\'{\i}}pedo, cujas superf{\'{\i}}cies emitem
radia{\c{c}}{\~a}o aos n{\'o}s situados na sua
vizinhan{\c{c}}a. Condut{\^a}ncias t{\'e}rmicas caracterizam as
trocas de calor. O modelo resulta em uma rede t{\'e}rmica formada
pelos nos e condut{\^a}ncias, caracterizando uma malha que {\'e}
an{\'a}loga a um circuito el{\'e}trico. O equacionamento
t{\'e}rmico surge do balan{\c{c}}o das trocas de calor em cada
no. A influ{\^e}ncia da divis{\~a}o nodal sobre a velocidade de
propaga{\c{c}}{\~a}o e o custo computacional s{\~a}o
analisados. Efetua-se simula{\c{c}}{\~o}es variando-se a
velocidade do vento e a quantidade de combust{\'{\i}}vel por
unidade de {\'a}rea do leito de combust{\'{\i}}vel. Observa-se
que a velocidade de propaga{\c{c}}{\~a}o est{\'a} diretamente
ligada as propriedades geom{\'e}tricas dos elementos de chama.
Quanto mais inclinados, maior ser{\'a} a velocidade de
propaga{\c{c}}{\~a}o na dire{\c{c}}{\~a}o de
inclina{\c{c}}{\~a}o. O modelo mostra ser flex{\'{\i}}vel para
lidar com situa{\c{c}}{\~o}es envolvendo propaga{\c{c}}{\~a}o
em superf{\'{\i}}cies com obst{\'a}culos. Os resultados obtidos
s{\~a}o encorajadores para a utiliza{\c{c}}{\~a}o do
m{\'e}todo nodal na modelagem da propaga{\c{c}}{\~a}o do fogo.
ABSTRACT: This work presents a new approach for a surface fire
spread model applicable to wildland fire modelling. The
mathematical method used in the modeling is the lumped parameter
approach. In this method the thermal domain is divided in a finite
number of volumes, supposed isothermal and with homogeneous
properties, called nodes. To each node are attributed a
temperature, a thermal capacitance and possibly internal heat
generation. Each node exchanges heat with its neighbors through
conductive condutances and interacts with the flames and the
ambient through radiatives conductances. When the node reach the
temperature of ignition, it is subject to an internal heat
generation that keeps on until total consumption of the vegetal
fuel. The ame over each node within the reaction zone is
approximated by a parallelopiped whose surfaces emits radiation to
the nodes positioned in its surrounding. Each flame has a
predetermined temperature-time prole model, geometrical properties
and a residence time that depend of ambient condictions. The
system of dierential equations, representing the net heat balance
of the nodes, is numerically solved, yielding, among other
results, the temporal evolution of the flame on the surface. The
conductance matrix, as well as the thermal capacitances and the
internal heat generation, is updated each time step. The in
influence of the nodal division on the fire spread rate and on the
computational cost is analyzed. Simulation are carried out varying
the wind speed and the fuel load. It is observed that the rate of
spread is directly related with the geometric properties of the
flame nodes. The model shows to be exible in situations involving
propagation in surfaces with obstacles. The results are
encouraging for the use of the lumped parameter approach in the
the surface fire spread modelling.",
committee = "Campos Velho, Haroldo Fraga de (presidente) and Macau, Elbert
Einstein Neher (orientador) and Ramos, Fernando Manuel
(orientador) and Muraoka, Issamu and Soares Filho, Britaldo
Silveira",
copyholder = "SID/SCD",
englishtitle = "Surface fire spread model based on lumped parameter approach",
language = "pt",
pages = "113",
ibi = "6qtX3pFwXQZGivnK2Y/PPm3R",
url = "http://urlib.net/ibi/6qtX3pFwXQZGivnK2Y/PPm3R",
targetfile = "publicacao.pdf",
urlaccessdate = "30 abr. 2024"
}