The structure of solutions near an extinction point in a semilinear heat equation with strong absorption: a formal approach

Abstract

We consider nonnegative solutions of the semilinear parabolic equation u t —u xx + u p = 0, -∞<x< +∞, t>0, 0<p<l, which vanish at the extinction point x = 0 at a time t = T. By means of formal methods, we derive a family of asymptotic expansions for solutions and interface curves (these last separating the regions where u = 0 and u> 0), as (x,t) approaches (0,T).