1279629_Broadbridge,P_2022.pdf (630.78 kB)
Exact Solutions of Hyperbolic Reaction-Diffusion Equations in Two Dimensions
journal contributionposted on 2023-12-01, 00:57 authored by Philip BroadbridgePhilip Broadbridge, J Goard
Exact solutions are constructed for a class of nonlinear hyperbolic reaction-diffusion equations in two-space dimensions. Reduction of variables and subsequent solutions follow from a special nonclassical symmetry that uncovers a conditionally integrable system, equivalent to the linear Helmholtz equation. The hyperbolicity is commonly associated with a speed limit due to a delay, between gradients and fluxes. With lethal boundary conditions on a circular domain wherein a species population exhibits logistic growth of Fisher-KPP type with equal time lag, the critical domain size for avoidance of extinction does not depend on. A diminishing exact solution within a circular domain is also constructed, when the reaction represents a weak Allee effect of Huxley type. For a combustion reaction of Arrhenius type, the only known exact solution that is finite but unbounded is extended to allow for a positive.