Time evolution (top to bottom) of the hot-bubble problem when solved using different well-balancing and reconstruction schemes (left to right) on a 128 × 192 grid. In all of the cases, entropy fluctuations ΔA/A are shown on the same color scale ranging from −10⁻³ (dark blue) through 0 (white) to 10⁻³ (dark red). The minimum and maximum values of ΔA/A in the whole simulation box are given in each panel’s inset. The amplitude of the initial entropy perturbation is (ΔA/A)_t = 0 = 10⁻³.