Temperature (left) and density (right) maps in the typical 3D snapshot of the red giant model constructed at different geometrical depth, z, with z = 0 set at log τ_Ross = 0 and increasing towards the stellar center. Contours are drawn at every 200 K (panels 1–3, top-down) and 500 K (panels 4–6) for temperature, and 0.5 dex (panels 1–4, top-down) and 0.1 dex (panels 5–6) for density. Vertical lines mark the x position (x = 7.77 × 10¹¹ cm) at which the 1D velocity profiles shown in Fig. 9 were constructed.