  We theoretically investigate how the acoustic radiation force and torque
arise on a small spheroidal particle immersed in a nonviscous fluid inside an
ideal cylindrical chamber. The ideal chamber comprises a hard top and bottom
(rigid boundary condition), and a soft or hard lateral wall. By assuming the
particle is much smaller than the acoustic wavelength, we present analytical
expressions of the radiation force and torque caused by an acoustic wave of
arbitrary shape. Unlike previous results, these expressions are given relative
to a fixed laboratory frame. Our model is showcased for analyzing the behavior
of an elongated metallic microspheroid (with a 10 : 1 aspect ratio) in a
half-wavelength acoustofluidic chamber with a few millimeters diameter. The
results show the radiation torque aligns the microspheroid along the nodal
plane, and the radiation force causes a translational motion with a speed of up
to one body length per second. At last, we discuss the implications of this
study to propelled nanorods by ultrasound.
