  We study nonhelical nano- and microparticles that, through a particular
shape, rotate when they are exposed to ultrasound. Employing acoustofluidic
computer simulations, we investigate the flow field that is generated around
these particles in the presence of a planar traveling ultrasound wave as well
as the resulting propulsion force and torque of the particles. We study how the
flow field and the propulsion force and torque depend on the particles'
orientation relative to the propagation direction of the ultrasound wave.
Furthermore, we show that the orientation-averaged propulsion force vanishes
whereas the orientation-averaged propulsion torque is nonzero. Thus, we reveal
that these particles can constitute nano- and microspinners that persistently
rotate in isotropic ultrasound.

Soft Condensed Matter;Mesoscale and Nanoscale Physics;Classical Physics;Computational Physics;Fluid Dynamics