In this paper, we study regularizing effects of the composition operator $S(t)\mathbb{ P}\partial$ for the Stokes semigroup $S(t)$ and the Helmholtz projection $\mathbb{ P}$ in a space of bounded functions. We establish new a priori $L^{ \infty}$-estimates of the operator $S(t)\mathbb{ P}\partial$ for a certain class of domains including bounded and exterior domains. They imply unique existence of mild solutions of the Navier-Stokes equations in a space of bounded functions.
Categories: math.AP