  Acoustic waves can generate steady streaming within a fluid owing to the
generation of viscous boundary layers near walls, of typical thickness
$\delta$. In microchannels, the acoustic wavelength $\lambda$ is adjusted to
twice the channel width $w$ to ensure a resonance condition, which implies the
use of MHz transducers. Recently though, intense acoustic streaming was
generated by acoustic waves of a few kHz (hence with $\lambda \gg w$), owing to
the presence of sharp-tipped structures of curvature radius at the tip $r_c$
smaller than $\delta$. The present study quantitatively investigates this
sharp-edge acoustic streaming via the direct resolution of the full
Navier-Stokes equation, using Finite Element Method. The influence of $\delta$,
$r_c$ and viscosity $\nu$ on the acoustic streaming performance are quantified.
Our results suggest choices of operating conditions and geometrical parameters,
via dimensionless quantities $r_c/\delta$ and $\delta/w$ and provide guidelines
on how to obtain strong, optimal sharp-edge acoustic streaming.
