Top: hydrodynamical model versus (bottom) our heuristic model for (a, d) number density, (b, e) radial velocity, and (c, f) rotational velocity distributions of the gas in the equatorial plane. Color bars label in units of cm⁻³ for number density and km s⁻¹ for velocities.The overlaid arrows represent the gas velocity vectors. The pericenter of WD is located on the straight white line, and the current orbital phase of the binary stars is at 65° before the pericenter.