We study exact multiplicity of positive solutions and the bifurcation curve of the
p-Laplacian
perturbed Gelfand problem from combustion theory
where
p>1,
φp(y)=|y|p−2y,
(φp(u′))′ is the one-dimensional
p-Laplacian,
λ>0 is the Frank–Kamenetskii parameter,
u(x) is the dimensionless temperature, and the reaction term
is the temperature dependence obeying the Arrhenius reaction-rate law. We find explicitly
such that, if the activation energy
, then the bifurcation curve is S-shaped in the
(λ,u∞)-plane. More precisely, there exist
0<λ*<λ*<∞ such that the
problem has exactly three positive solutions for
λ*<λ<λ*, exactly two positive solutions for
λ=λ* and
λ=λ*, and a unique positive solution for
0<λ<λ* and
λ*<λ<∞.