Around the periphery of the disk, a shock front or wall of water forms;outside the shock front, the water moves slower than the local wave speed (analogous to the subsonic interstellar medium).

• 在浅盘的周围，形成激波前缘或水墙，在激波前缘之外，水的运动速度低于该处的波速（类似于次音速的星际介质）。