Vertical slices through the disk along the azimuthal direction showing the density distribution and velocity field. Arrow lengths are not to scale. (a) The bow shock is generated by a star-disk collision, and downstream material fills the low-density cavity left by the star’s passage, producing backward ejecta; (b) the perturbation induced by the sBH-disk interaction, exhibiting a bow-shock-like structure. The black hole attracts surrounding material along its path, producing a pronounced density enhancement and quickly generates backward ejecta. (The size of the black-filled part is the Bondi radius of the sBH.)