Nonstationary Contrasting Structures for the Generalized Kolmogorov-Petrovskiy-Piskunov Equation

The solution to the generalized Kolmogorov-Petrovskiy-Piskunov (GKPP) equation is shown to have a contrasting structure. Contrasting structures (CSs) are characterized by the existence of wide areas with a small field gradient separated by narrow internal transition layers (ITLs) with a large field gradient. The ITLs in an inhomogeneous medium are shown to drift and the drift velocity is determined. The CS drift velocity for the GKPP equation is compared with a simpler model of the reaction-advection-diffusion equation.