Kippenhahn diagrams of the simulation with q = 0.25, C_d = 0.23, and C_h = 4.0. In panel a, the radial velocity is shown in terms of the local escape velocity; layers colored in red have a radial velocity higher than the local escape velocity. Panels b, c, and d show the ionization fractions of H II, HeII, and He III, respectively. The heating kernel as described in Eq. (15) is shown in panel e, and the specific heating rate in panel f. The red line indicates the orbital separation between the companion and the core of the giant star. The dotted gray region is heated during the CE simulation. The dashed cyan line shows R_τ = 10, which traces the hydrogen-recombination radius. The dashed gray lines represent envelope-mass fractions of 0.95, 0.9, 0.8, 0.6, 0.4, 0.2, 0.1, 0.06, 0.04, and 0.03 from the surface toward the center, and visualize the expansion of the envelope. The white patches in panel a show layers that have an inward (negative) radial velocity.