Rigorous derivation of the Kuramoto-Sivashinsky equation in a 2D weakly nonlinear Stefan problem.

Claude-Michel Brauner (1) , Josephus Hulshof (2) , Luca Lorenzi (3)

1 IMB - Institut de Mathématiques de Bordeaux
2 Department of Computer Science [Amsterdam]
3 Dipartimento di Matematica

In this paper we are interested in a rigorous derivation of the Kuramoto-Sivashinsky equation (K--S) in a Free Boundary Problem. As a paradigm, we consider a two-dimensional Stefan problem in a strip, a simplified version of a solid-liquid interface model. Near the instability threshold, we introduce a small parameter $\varepsilon$ and define rescaled variables accordingly. At fixed $\varepsilon$, our method is based on: definition of a suitable linear 1D operator, projection with respect to the longitudinal coordinate only, Lyapunov-Schmidt method. As a solvability condition, we derive a self-consistent parabolic equation for the front. We prove that, starting from the same configuration, the latter remains close to the solution of K--S on a fixed time interval, uniformly in $\varepsilon$ sufficiently small.

Mots clés: pseudo-differential operators; Kuramoto-Sivashinsky equation; front dynamics; Stefan problems; singular perturbations

Domaines: Equations aux dérivées partielles [math.AP]

Claude-Michel Brauner, Josephus Hulshof, Luca Lorenzi. Rigorous derivation of the Kuramoto-Sivashinsky equation in a 2D weakly nonlinear Stefan problem.. 2009. ⟨hal-00404251⟩