Spectra of the radial kinetic energy component for the and AUSM⁺-up solver at a resolution of 810 × 540² cells and an energy boosting of b = 3 × 10⁴. The amplitudes are normalized to unity at ℓ = 50 for better comparability. Dotted vertical lines mark the angular degree ℓ at which the relative deviation from the Kolmogorov-law is one decade. For the solver this happens at ℓ ≈ 470, for the AUSM⁺-up solver at ℓ ≈ 920. The horizontal axis is truncated at the spectral width of the applied window function (ℓ_max = 25).