  The radiation force exerted on an object by an acoustic wave is a widely
studied phenomenon since the early work of Rayleigh, Langevin and Brillouin and
has led in the last decade to tremendous developments for acoustic
micromanipulation. Despite extensive work on this phenomenon, the expressions
of the acoustic radiation force applied on a particle have so far been derived
only for a steady particle, hence neglecting the effect of its displacement on
the radiated wave. In this work we study the acoustic radiation force exerted
on a monopolar source translating at a constant velocity small compared to the
sound speed. We demonstrate that the asymmetry of the emitted field resulting
from Doppler effect induces a radiation force on the source opposite to its
motion.
