  In a two-dimensional version of the modified Hasegawa-Wakatani (HW) model,
which describes electrostatic resistive drift wave turbulence, the resistive
coupling between vorticity and density does not act on the zonal components
($k_{y}=0$). It is therefore necessary to modify the HW model to treat the
zonal components properly. The modified equations are solved numerically, and
visualization and analysis of the solutions show generation of stable zonal
flows, through conversion of turbulent kinetic energy, and the consequent
turbulence and transport suppression. It is demonstrated by comparison that the
modification is essential for generation of zonal flows.
