Transition fronts of time periodic bistable reaction-diffusion equations in R-N
Résumé
This paper is concerned with the existence and qualitative properties of transition fronts for time periodic bistable reaction-diffusion equations in R-N. We first show that any almost-planar transition front is actually planar, regardless of the number of transition layers. Then we prove that all transition fronts admit a global mean speed gamma and it holds gamma = vertical bar c vertical bar, where c is the speed of the planar traveling front. Finally we establish the existence of a transition front in R-N that is not a standard traveling front. Such a front behaves like three moving time periodic planar fronts as time goes to -infinity and like a time periodic V-shaped traveling front as time goes to infinity.