(a) and (b) Absolute values of the velocity for the two‐dimensional simulation at times t = 0.525 s and t = 1.047 s, respectively, color‐coded in units of 10⁸ cm s⁻¹. The computation was performed in an angular wedge of 90° between +45° and −45° around the equatorial plane. The PNS has contracted to a radius of about 21 km at the given times. (c) and (d) Relative deviations of the electron fraction Y_e from the angular means Y_e at each radius for the same two instants. Maximum deviations are of the order of 30%. Lepton‐rich matter rises while deleptonized material sinks in. Comparison of both times shows that the inner edge of the convective layer moves inward from about 8.5 km at t = 0.525 s to less than 2 km at t = 1.047 s.