Distribution of the x-component of the gas velocity in the x-direction at the midplane, υ_x,max(x). The solid blue line is given by Eq. (31). The yellow dots were obtained from m02-hw0 (panel a), m02-hw001 (panel b), m02-hw003 (panel c), and m02-hw01 (panel d). We sampled the gas velocity at each radial grid of hydro-dynamical simulations where the absolute value of the gas velocity was the maximum within the limited region, , and .