Temporal evolution of magnetic energy and kinetic energy in the simulations of different σ_y. The color of the lines represents five experiments, magenta, red, cyan, blue, and green represent CASE I, IX, II, III, IV, respectively. A: evolution of magnetic energy E_M (solid lines) and kinetic energy E_K (dotted lines). B: releasing rate of magnetic energy and increasing rate of kinetic energy of five experiments. The vertical dashed lines are shown for denoting the transition time of from pre-eruption to eruption. In the ordinates of all panels, the normalized unit is the potential field energy based on each magnetogram.