  Outflows launched from a remnant disc of compact binary merger may have
essential contribution to the kilonova emission. Numerical calculations are
conducted in this work to study the structure of accretion flows and outflows.
By the incorporation of limited-energy advection in the hyper-accretion discs,
outflows occur naturally from accretion flows due to imbalance between the
viscous heating and the sum of the advective and radiative cooling. Following
this spirit, we revisit the properties of the merger outflow ejecta. Our
results show that around $10^{-3} \sim 10^{-1} M_\odot$ of the disc mass can be
launched as powerful outflows. The amount of unbound mass varies with the disc
mass and the viscosity. The outflow-contributed peak luminosity is around
$10^{40} \sim 10^{41}$ erg/s. Such a scenario can account for the observed
kilonovae associated with short gamma-ray bursts, including the recent event
AT2017gfo (GW170817).
