  Acoustic streaming is an ubiquitous phenomenon resulting from time-averaged
nonlinear dynamics in oscillating fluids. In this theoretical study, we show
that acoustic streaming can be suppressed by two orders of magnitude in major
regions of a fluid by optimizing the shape of its confining walls. Remarkably,
the acoustic pressure is not suppressed in this shape-optimized cavity, and
neither is the acoustic radiation force on suspended particles. This basic
insight may lead to applications, such as acoustophoretic handling of nm-sized
particles, which is otherwise impaired by acoustic~streaming.
