Top: characteristic amplitude of v/c_s and δρ/ρ for the hydro model with M ~ 0.5, doubling the numerical viscosity, i.e. using 2 × lower resolution (similar to the Spitzer value; dashed lines). Spectra are convergent, except at small scales where the increased numerical diffusivity damps both v and δρ/ρ at about twice the original dissipation scale. The density cascade is affected in a slightly different way by the larger diffusivity; some deviations from the classic advection theory of tracers are thus expected (Sect. 5.2.1). Bottom: spectrum of the above model extracted in the full box (solid) and in the center (dashed; <r₅₀₀/ 4), where stratification is less prominent. Turbulence and density perturbations are overall homogeneous, despite the cluster stratification (compare with Fig. 4).