Derivative loss for Kirchhoff equations with non-Lipschitz nonlinear term

Ghisi, Marina¹ ; Gobbino, Massimo²

¹ Università degli Studi di Pisa, Dipartimento di Matematica “Leonida Tonelli”, Largo B. Pontecorvo, 5, Pisa, Italia
² Università degli Studi di Pisa, Dipartimento di Matematica Applicata “Ulisse Dini”, Via Filippo Buonarroti, 1c, 56127 Pisa, Italia

Annali della Scuola Normale Superiore di Pisa - Classe di Scienze, Série 5, Tome 8 (2009) no. 4, pp. 613-646

Résumé

In this paper we consider the Cauchy boundary value problem for the integro-differential equation $u_{tt}-m\left({\int }_{\Omega }^{}{\left|\nabla u\right|}^{2}dx\right)\Delta u=0\text{in}\Omega \times [0,T)$ with a continuous nonlinearity $m:[0,+\infty )\to [0,+\infty )$. It is well known that a local solution exists provided that the initial data are regular enough. The required regularity depends on the continuity modulus of $m$. In this paper we present some counterexamples in order to show that the regularity required in the existence results is sharp, at least if we want solutions with the same space regularity of initial data. In these examples we construct indeed local solutions which are regular at $t=0$, but exhibit an instantaneous (often infinite) derivative loss in the space variables.

Détail

Classification : 35L70, 35L80, 35L90