Axial distribution of the acceleration by effective gravity at the jet boundary for 2D RMHD case MHD1-2D (top) and 3D RMHD case MHD1 (bottom). Different color lines indicate the effective gravity at different radii of simulations, R = R_jb (blue dotted), R_jb − 0.02 (orange dotted), R_jb − 0.04 (green solid), and R_jb − 0.06, where R_jb is the radius of the jet boundary. Star marks are the azimuthal averaged radial acceleration calculated directly from the radius variations. The error bar is the standard deviation of the averages.