On the blow-up of solutions for the b-equation

Abstract

We establish blow-up results for a family of equations under various classes of initial data. It turns out that it is the shape instead of the size and smoothness of the initial data which influences breakdown in finite time. Then, infinite propagation speed for the shallow water equations is proved in the following sense: the corresponding solution u(t, x) with compactly supported initial datum u0(x) does not have compact x-support any longer in its lifespan.