Simulation results for the flux feeding processes in a flux rope system with double-layer configuration. Panel (a) shows the new initial state. Panels (b1)–(b3) show the evolution for the case with C_E = 0.5, and the inset in panel (b1) corresponds to the region marked by the red box in panel (b). Panels (c1)–(c4) and panels (d1)–(d4) show the results for the cases with C_E = 1.5 and C_E = 2.0, respectively. The meanings of the symbols and colors are the same as in Fig. 1.