The development of acoustic levitation systems has provided a technolo
gy with which to undertake fundamental studies of free drop dynamics a
s well as processing experiments. Acoustic levitation chambers utilize
radiation forces to position the drop. Moreover, drop oscillations ca
n be induced via frequency modulation of the acoustic wave. The modula
ted acoustic radiation vector, itself a projection of the radiation st
ress, acts as the driving force for the drop oscillations. If the acou
stic field is considered to be inviscid, only the radial component of
the radiation force exists. In order to account for the tangential for
cing, it is necessary that the effects of viscosity be included in the
acoustic field. This work determines the viscous acoustic field. The
effects of viscosity contribute in a thin layer near the drop/host flu
id interface. The method of composite expansions is employed in the de
termination of the acoustic field with viscous effects taken into acco
unt.