We consider the Navier-Stokes system for compressible fluids in a low Mach number regime. The aim is to get the existence of a strong solution on an interval of time independent of the Mach number. The main issue, which also occurs when studying the system in a fixed domain with a slip boundary condition, is the conjonction of the time oscillations and a boundary layer in space. Joint work with Changzhen Sun and N. Masmoudi.