Abstract
In this paper, we consider an initial-value problem for a non-linear hyperbolic Fisher equation. The nonlinear hyperbolic Fisher equation is given by
epsilon u(tt) + u(t) = u(xx) + F(u) + epsilon F(u)(t),
where epsilon > 0 is a parameter and F(u) = u(1 - u) is the classical Fisher kinetics. The initial data considered is positive, having unbounded support with exponential decay of O(e(-sigma x)) at large x (dimensionless distance), where sigma > 0 is a parameter. It is established, via the method of matched asymptotic expansions, that the large time structure of the solution to the initial-value problem involves the evolution of a propagating wavefront which is either of reaction - diffusion or of reaction - relaxation type. In particular, the wave speed for the large t (dimensionless time) permanent form travelling wave (PTW), which may be subsonic (reaction-diffusion), sonic (reaction-relaxation) or supersonic (reaction-relaxation), the asymptotic correction to the wave speed and the rate of convergence of the solution onto the PTW are obtained for all values of the parameters epsilon and sigma.
Original language | English |
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Pages (from-to) | 870-903 |
Number of pages | 34 |
Journal | IMA Journal of Applied Mathematics |
Volume | 74 |
DOIs | |
Publication status | Published - 1 Jan 2009 |
Keywords
- thin porous layer
- travelling wavefronts
- hyperbolic Fisher model
- matched asymptotic expansions
- oil recovery
- matched asymptotics