# Large time behavior of fronts governed by eikonal equations

### Guy Barles

Université de Tours, France### Jean-Michel Roquejoffre

Université Paul Sabatier, Toulouse, France

## Abstract

Motivated by a model of solid combustion in heterogeneous media, we investigate the time-asymptotic behaviour of flame fronts evolving with a periodic space-dependent normal velocity; using the so-called ``level set approach'' we are led to study the large time behaviour of solutions of eikonal equations. We first provide a general approach which shows that the asymptotic normal velocity of such a flame front depends only on its normal direction and is given by the homogenized Hamiltonian of the eikonal equation. Then we turn to a more precise study of the asymptotic behaviour of the flame front when the initial front is a graph of a periodic function: in this case, the front moves asymptotically with a constant normal velocity and we are able to prove that, in coordinates moving with this constant velocity, the front has a time-periodic asymptotic behaviour in the following two cases: (i) when there is a straight line of maximal speed, and (ii) when the space dimension is 2. These results are obtained by using homogenization, control theory and dynamical systems methods (Aubry--Mather sets).

## Cite this article

Guy Barles, Jean-Michel Roquejoffre, Large time behavior of fronts governed by eikonal equations. Interfaces Free Bound. 5 (2003), no. 1, pp. 83–102

DOI 10.4171/IFB/73