Dependence of the Rayleigh-Taylor instability on the effective Mach number. The maximum amplitude of the y-component of the velocity at time = 2.5 in PVS form with constant ξ (red solid with diamond), in PMS form with constant ξ (blue solid with cross), in PVS form with constant C_max (red dotted with triangle), and in PMS form with constant C_max (blue dotted with box). The horizontal dashed line shows the reference simulation results without the RSST (ξ = 1) in 4096 × 4096 grids.