Abstract: The identification of sound and vortex and their interaction in nonuniform flow are discussed using split technique of velocity vector and asymptotic expansions.In particular,second order interaction in shear flow is considered.The result is used to explain the phenomena in airfoil flow controled by sound.After calculating the amplification of second order vortex,the effective vortex patterns and the relation between vortex frequency and sound frequency are obtained.In addition,the threshold value of sound ...