The prediction of near field acoustic velocity is necessary when using equivalent source method and evaluating multi acoustic fields problem. According to the idea of acoustic analogy, this paper induces a vector wave equation of aeroacoustics by rearranging the conservation equations of mass and momentum with a permeable surface. Then, an analytical formulation of the acoustic velocity, called formulation V2A, is derived for sources in a quiescent medium by solving the vector wave equation with the free-space Green’s function. The validity of the formulation is confirmed by numerical results for a stationary monopole, a stationary dipole source, and a rotating monopole source in a quiescent medium. The result indicates that the predication of formulation V2A is nearly identical to the exact solutions no matter in far-field or near-field.
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