Evolution snapshots of MFRs for cases refTDa, htirep, and ltirep at t = 2.4, 1.5, and 1.5, respectively. The Alfvén time τ_a for these cases equals to 0.21, as shown in Table 1. The geometry of MFRs is shown by the gray current isosurfaces. Panel a: in case refTDa with α = 1, the MFR crashes downward to the photosphere. Panel b: in case htirep with α = 0, no kink happens, but only an expansion occurs. Panel c: in case ltirep with α = 0.9, internal gas pressure balances the toroidal curvature effect at the early stage of this simulation.