Volume gas density in a r-θ plane, in units of M_A/au³ and logarithmic scale, from the 3D model of Figure 1. The orbital phase of the binary corresponds to a time ≈0.06 T (top) and ≈0.13 T (middle), after pericenter passage, and ≈0.1 T prior to apocenter passage (bottom). The curves with arrows are streamlines of the gas velocity projected in the r-θ plane (different streamline colors are used to enhance the contrast against the density color-map). The waves excited by the secondary propagate inward, stirring the vertical and radial motion of the gas.