Hostname: page-component-586b7cd67f-rcrh6 Total loading time: 0 Render date: 2024-11-22T08:05:30.105Z Has data issue: false hasContentIssue false

The asymptotics of extinction in nonlinear diffusion reaction equations

Published online by Cambridge University Press:  17 February 2009

R. E. Grundy
Affiliation:
Department of Mathematical Sciences, University of St. Andrews, Scotland.
Rights & Permissions [Opens in a new window]

Abstract

Core share and HTML view are not available for this content. However, as you have access to this content, a full PDF is available via the ‘Save PDF’ action button.

In this paper we consider the asymptotics of extinction for the nonlinear diffusion reaction equation

with non-negative initial data possessing finite support. For t > 0, both solution and support vanish as t → T and x → x0. With T as the extinction time we construct the asymptotic solution as τ = T – t → 0 near the extinction point x0 using matched expansions. Taking x0= 0, we first form an outer expansion valid when η =xt–(m–p)/2 (1–p) = 0(1). This is nonuniformly valid for large |η| and has to be replaced by an intermediate expansion valid for |x| = O−1/l0) where l0 is an even integer greater than unity. If p + m ≥ 2 this expansion is uniformly valid while for p + m < 2, there are regions near the edge of the support where diffusion becomes important. The zero order solution in these inner regions is discussed numerically.

Type
Research Article
Copyright
Copyright © Australian Mathematical Society 1992

References

[1] Galaktionov, V. A., Herrero, M. A. and Velazquez, J. J. L., “The structure of solutions near an extinction point in a semilinear heat equation with strong absorption”, Preprint (1990).Google Scholar
[2] Herraro, M. A. and Friedman, A., “Extinction properties of semilinear heat equations with strong absorption”, J. Math. Anal, and Appl. 124 (1987).Google Scholar
[3] Kalashnikov, A. S., “The propagation of disturbances in problems of nonlinear heat conduction with absorption”, USSR Comp. Math, and Math. Physics 14 (1974)CrossRefGoogle Scholar
[4] Kalashnikov, A. S., “On the dependence of properties of solutions of parabolic equations in unbounded domains on the behaviour of the coefficients at infinity”, Math. USSR Sbornik 53 No. 2 (1986).CrossRefGoogle Scholar
[5] Kersner, R., “The behaviour of temperature fronts in media with nonlinear thermal conductivity under absorption”, Vestnik Moskovskogo Universiteta. Matematika 33 No. 5 (1978).Google Scholar