  While traditional approaches to prevent the carbuncle phenomenon in gas
dynamics simulations increase the viscosity on entropy and shear waves near
shocks, it was quite recently suggested to instead decrease the viscosity on
the acoustic waves for low Mach numbers. The goal is to achieve what, in this
paper, we call Mach number consistency: for all waves, the numerical viscosity
decreases with the same order of the Mach number when the Mach number tends to
zero. We take the simple approach that was used for the proof of concept
together with the simple model for the increased numerical viscosity on linear
waves and investigate the possibilities of combining both in an adaptive manner
while locally maintaining Mach number consistency.
