  We present a fully discrete approximation technique for the compressible
Navier-Stokes equations that is second-order accurate in time and space,
semi-implicit, and guaranteed to be invariant domain preserving. The
restriction on the time step is the standard hyperbolic CFL condition, ie $\tau
\lesssim \mathcal{O}(h)/V$ where $V$ is some reference velocity scale and $h$
the typical meshsize.
