Far-field acoustic analysis for a finite long pulsating cylinder considering effects of free liquid surface

Abstract

Here, an acoustic scattering model of a finite long pulsating cylinder considering effects of free liquid surface was established, and an analytical method to solve the far-field sound pressure was proposed. Using the image method combined with Graf's addition theorem, the expression for sound pressure in wavenumber domain was deduced. Then, the far-field sound pressure was derived using the stationary phase method. The study results showed that radiated sound and scattered one produce a dipole-like effect due to effects of free liquid surface; the far-field sound pressure's directional sectioning increases with increase in immersion depth or frequency; the field point sound pressure periodically fluctuates with increase in immersion depth, while the scattering sound pressure fluctuates and decays; if frequency is low and immersion depth is larger than five times of cylinder radius, the mutual scattering effect can be neglected, this provides a reference for how to properly ignore the mutual scattering effect between target and interface within a limited space.