Equivalence of expressions for the acoustic radiation force on cylinders

Using an appropriate grouping of terms, a radiation force expression for cylinders in a standing wave based on far-field scattering [Wei et al., J. Acoust. Soc. Am. 116, 202–208 (2004)] is transformed to an expression given elsewhere [F. G. Mitri, Eur. Phys. J. B 44, 71–78 (2005)]. Mitri’s result is from a near-field derivation for the specific case of a circular cylinder. The far-field derivation also applies to noncircular objects having mirror symmetry about the incident wave vector. Some aspects of far-field derivations of optical and acoustical radiation forces are noted as are some implications for the radiation force on cylinders in travelling waves.